Patent Grant
11480411
The present invention relates to instruments and methods for measuring range to a target object surface, aiming a rifle, external ballistics and methods for predicting projectile's trajectory. This application also relates to projectile weapon aiming systems such as rifle scopes, to sensors for measuring range, reticle configurations for projectile weapon aiming systems, and to associated methods of compensating for a projectile's external-ballistic behavior while developing a field expedient firing solution.
Rifle marksmanship has been continuously developing over the last few hundred years, and now refinements in materials and manufacturing processes have made increasingly accurate aimed fire possible. These refinements have made previously ignored environmental and external ballistics factors more significant as sources of aiming error.
The term “rifle” as used here, means a projectile controlling instrument or weapon configured to aim and propel or shoot a projectile, and rifle sights or projectile weapon aiming systems are discussed principally with reference to their use on rifles and embodied in telescopic sights commonly known as rifle scopes. It will become apparent, however, that projectile weapon aiming systems may include aiming devices other than rifle scopes, and may be used on instruments or weapons other than rifles which are capable of controlling and propelling projectiles along substantially pre-determinable trajectories (e.g., rail guns or cannon). The prior art provides a richly detailed library documenting the process of improving the accuracy of aimed fire from rifles (e.g., as shown in
Most shooters or marksmen, whether hunting or target shooting, understand the basics. The primary factors affecting aiming accuracy are (a) the range or distance to the target which determines the arcuate trajectory or “drop” of the bullet in flight and the time of flight (“TOF”), and (b) the windage, wind deflection factors or lateral drift due to transverse or lateral forces acting on the bullet during TOF. Experienced marksmen account for these two factors when aiming. Precision long-range shooters such as military and police marksmen (or “snipers”) often refer to references including military and governmental technical publications such as the following:
A number of patented rifle sights or projectile weapon aiming systems have been developed to help marksmen account for the elevation/range and windage factors when aiming. For example, U.S. Pat. No. 7,603,804 (to Zadery et al) describes a riflescope made and sold by Leupold & Stevens, Inc., with a reticle including a central crosshair defined as the primary aiming mark for a first selected range (or “zero range”) and further includes a plurality of secondary aiming marks spaced below the primary aiming mark on a primary vertical axis. Zadery's secondary aiming marks are positioned to compensate for predicted ballistic drop at selected incremental ranges beyond the first selected range, for identified groups of bullets having similar ballistic characteristics.
Zadery's rifle scope has variable magnification, and since Zadery's reticle is not in the first focal plane (“F1”) the angles subtended by the secondary aiming marks of the reticle can be increased or decreased by changing the optical power of the riflescope to compensate for ballistic characteristics of different ammunition. The rifle scope's crosshair is defined by the primary vertical line or axis which is intersected by a perpendicular horizontal line or primary horizontal axis. The reticle includes horizontally projecting windage aiming marks on secondary horizontal axes intersecting selected secondary aiming marks, to facilitate compensation for the effect of crosswinds on the trajectory of the projectile at the selected incremental ranges At each secondary aiming mark on the primary vertical axis, the laterally or horizontally projecting windage aiming marks project symmetrically (left and right) from the vertical axis, indicating a windage correction for wind from the shooter's right and left sides, respectively. That windage correction is wrong, however, as will be illustrated and described below.
Beyond bullet drop over a given range and basic left-right or lateral force windage compensation, there are several other ballistic factors which result in lesser errors in aiming. As the inherent precision of rifles and ammunition improves, it is increasingly critical that these other factors be taken into consideration and compensated for, in order to make an extremely accurate shot. These factors are especially critical at very long ranges, (e.g., approaching or beyond one thousand yards). Many of these other factors were addressed in this applicant's U.S. Pat. No. 7,325,353 (to Cole & Tubb) which describes a riflescope reticle including a plurality of charts, graphs or nomogrpahs arrayed so a shooter can solve the ranging and ballistic problems required for correct estimation and aiming at a selected target. The '353 patent's scope reticle includes at least one aiming point field to allow a shooter to compensate for range (with elevation) and windage, with the “vertical” axis precisely diverging to compensate for “spin drift” and precession at longer ranges. Stadia for determining angular target dimension(s) are included on the reticle, with a nomograph for determining apparent distance from the apparent dimensions being provided either on the reticle or external to the scope. Additional nomographs are provided for the determination and compensation of non-level slopes, non-standard density altitudes, and wind correction, either on the reticle or external to the riflescope.
The elevation and windage aim point field (50) in the '353 patent's reticle was comparable, in one respect, to traditional bullet drop compensation reticles such as the reticle illustrated in the Zaderey '804 patent, but includes a number of refinements such as the compensated elevation or “vertical” crosshair 54, which can be seen to diverge laterally away from a true vertical reference line 56 (e.g., as shown in FIG. 3 of the '353 patent), to the right (i.e., for a rifle barrel with rifling oriented for right hand twist). The commercial embodiment of the '353 patent reticle was known as the DTAC™ Reticle, and the RET-2 version of the DTAC reticle is illustrated in
The compensated elevation or “vertical” crosshair of the DTAC™ reticle was useful for estimating a ballistic effect of the bullet's gyroscopic precession known as “spin drift” caused by the bullet's stabilizing axial rotation or spin, which is imparted on the bullet by the rifle barrel's inwardly projecting helical “lands” which bear upon the bullet's circumferential surfaces as the bullets accelerates distally down the barrel. Spin drift is due to an angular change of the axis of the bullet in flight as it travels downrange in an arcuate ballistic flight path. While various corrections have been developed for most of these factors, the corrections were typically provided in the form of programmable electronic devices or earlier in the form of logbooks developed over time by precision shooters. Additional factors affecting exterior ballistics of a bullet in flight include atmospheric variables, specifically altitude and barometric pressure, temperature, and humidity.
Traditional telescopic firearm sight reticles have been developed with markings to assist the shooter in determining the apparent range of a target. A nearly universal system has been developed by the military for artillery purposes, known as the “mil-radian,” or “mil,” for short. This system has been adopted by most of the military for tactical (e.g., sniper) use, and was subsequently adopted by most of the sport shooting world. The mil is an angle having a tangent of 0.001. A mil-dot scale is typically an array of dots (or similar indicia) arrayed along a line which is used to estimate or measure the distance to a target by observing the apparent target height or span (or the height or span of a known object in the vicinity of the target). For example, a target distance of one thousand yards would result in one mil subtending a height of approximately one yard, or thirty six inches, at the target. This is about 0.058 degree, or about 3.5 minutes of angle. It should be noted that although the term “mil-radian” implies a relationship to the radian, the mil is not exactly equal to an angle of one one thousandth of a radian, which would be about 0.057 degree or about 3.42 minutes of angle. The “mil-dot” system, based upon the mil, is in wide use in scope reticle marking, but does not provide a direct measure for determining the distance to a target without first having at least a general idea of the target size, and then performing a mathematical calculation involving these factors. Confusingly, the US Army and the US Marine Corps do not agree on these conversions exactly (see, e.g., Refs 5 and 6), which means that depending on how the shooter is equipped, the shooter's calculations using these conversions may change slightly.
The angular measurement known as the “minute of angle,” or MOA is used to measure the height or distance subtended by an angle of one minute, or one sixtieth of one degree. At a range of one hundred yards, this subtended angle spans slightly less than 1.05 inches, or about 10.47 inches at one thousand yards range. It will be seen that the distance subtended by the MOA is substantially less than that subtended by the mil at any given distance, i.e. thirty six inches for one mil at one thousand yards but only 10.47 inches for one MOA at that range. Thus, shooters have developed a rather elaborate set of procedures to calculate required changes to sights (often referred to as “clicks”) based on a required adjustment in a bullet's point of impact (e.g., as measured in “inches” or “minutes”).
Sight adjustment and ranging methods have been featured in a number of patents Assigned to Horus Vision, LLC, including U.S. Pat. Nos. 6,453,595 and 6,681,512, each entitled “Gunsight and Reticle therefore” by D. J. Sammut and, more recently, U.S. Pat. No. 7,832,137, entitled “Apparatus and Method for Calculating Aiming Point Information” by Sammut et al. These patents describe several embodiments of the Horus Vision™ reticles, which are used in conjunction with a series of calculations to provide predicted vertical corrections (or holdovers) for estimated ranges and lateral corrections (or windage adjustments), where a shooter calculates holdover and windage adjustments separately, and then selects a corresponding aiming point on the reticle.
In addition to the general knowledge of the field of the present invention described above, the applicant is also aware of certain foreign references which relate generally to the invention. Japanese Patent Publication No. 55-36,823 published on Mar. 14, 1980 to Raito Koki Seisakusho KK describes (according to the drawings and English abstract) a variable power rifle scope having a variable distance between two horizontally disposed reticle lines, depending upon the optical power selected. The distance may be adjusted to subtend a known span or dimension at the target, with the distance being displayed numerically on a circumferential external adjustment ring. A prism transmits the distance setting displayed on the external ring to the eyepiece of the scope, for viewing by the marksman.
In order to provide a more structured background and a system of nomenclature, we refer again to
While an exemplary conventional variable power scope 10 is used in the illustrations, fixed power (e.g., 10×, such as the M3A scope) are often used. Such fixed power scopes have the advantages of economy, simplicity, and durability, in that they eliminate at least one lens and a positional adjustment for that lens. Such a fixed power scope may be suitable for many marksmen who generally shoot at relatively consistent ranges and targets.
Variable power scopes include two focal planes. The reticle screen or glass 16 used in connection with the reticles of the present invention is preferably positioned at the first or front focal plane (“FP1”) between the distal objective lens 12 and erector lens 18, in order that the reticle thereon will change scale correspondingly with changes in magnification as the power of the scope is adjusted. This results in reticle divisions subtending the same apparent target size or angle, regardless of the magnification of the scope. In other words, a target subtending two reticle divisions at a relatively low magnification adjustment, will still subtend two reticle divisions when the power is adjusted, to a higher magnification, at a given distance from the target. This reticle location is often preferred when used in combination with a variable power firearm scope.
Alternatively, reticle screen 16 may be placed at a second or rear focal plane between the zoom lens 20 and proximal eyepiece 14. Such a second focal plane reticle will remain at the same apparent size regardless of the magnification adjustment to the scope, which has the advantage of providing a full field of view to the reticle at all times. However, the reticle divisions will not consistently subtend the same apparent target size with changes in magnification, when the reticle is positioned at the second focal plane in a variable power scope.
The horizontal crosshair 32 and central aiming dot line 34 define a single aim point 38 at their intersection. The multiple aim point field 30 was formed of a series of horizontal rows which are seen in
Most of the horizontal rows in
In order to use the Tubb™ DTAC™ elevation and windage aim point field 30, the marksman needed a reasonably close estimate of the range to the target (see, e.g.,
In
Both of the reticles discussed above (30 and 50) represented significant aids for precision shooting over long ranges, such as the ranges depicted in
The above described systems are now in use in scope reticles, but these prior art systems have been discovered to include subtle but significant errors arising from recently observed external ballistic phenomena, and the observed error has been significant enough (e.g., exceeding one MOA) at ranges well within the operationally significant military or police sniping range limits (e.g., 1000-1400 yards) to require further improvements.
The prior art systems often require the marksman or shooter to bring a companion (e.g., a coach or spotter) who may be required to bring additional optics or instruments for observation and measurement and may also be required to bring along computer-like devices such as a transportable personal digital assistant (“PDA”) or a smart phone (e.g., an iPhone™ or a Blackberry™ programmed with an appropriate software application or “app”) for solving ballistics problems while in the field.
These prior art systems also require the marksman or their companion to engage in too many evaluations and calculations while in the field, and even for experienced long-range shooters, those evaluations and calculations usually take up a significant amount of time. If the marksman is engaged in military or police tactical or sniping operations, lost time when aiming may be extremely critical, (e.g., as noted in Refs 5 and 6). Another complicating factor is that accurately estimating or measuring the distance or range to a selected target can be difficult in certain situations. In response, many shooters have begun using Laser Range Finder (“LRF”) instruments to measure Line of Sight (“LOS”) range (see, e.g., 29 in
The prior art includes a number of gun and rifle scope assemblies which incorporate a form of range sensing or range-finding mechanism which are configured to address bullet drop over a given trajectory. For example, U.S. Pat. No. 6,269,581, issued to Groh, describes a range compensating rifle scope which utilizes laser range-finding and microprocessor technology to compensate for bullet drop over a given trajectory range. The scope includes a laser rangefinder which senses the distance between the user and a target that is centered in the scope crosshairs. The user enters a muzzle velocity value together with input for bullet weight and altitude, following which the microprocessor is programmed to calculate a distance that the bullet traveling at the selected velocity will drop while traversing the distance calculated by the laser rangefinder, taking into consideration reduced drag at higher altitudes and the weight of the bullet (but not taking into consideration the effects of slope angle or the effects of crosswinds with gyroscopic precession). Based upon Groh's calculated value, a second LCD image crosshair is superimposed in the scope's viewfinder, indicating the proper elevation at which to aim the rifle to compensate for calculated bullet drop.
Exemplary LRF Scope Technical Background and Nomenclature:
U.S. Pat. No. 7,516,571, issued to Scrogin, is an improvement over Groh's work in that the scope assembly couples the Laser Range Finder (“LRF”) electronics display driver and optics (e.g., prism) to provide a reticle display field as a horizontal line, as illustrated in this Application's Prior Art
Scrogin's range-finding component subassembly L16 is, as illustrated in
Scrogin's system L10 includes amplifier L44 in operative communication at one end with an infrared detector L46, located in proximity to the prism L28, as well as communicating with the timer control circuit L40. The infrared detector L46 is constructed such that it is capable of being illuminated through the objective lens L30, thus offering the advantage of a relatively large lens for the IR detector to “see through”, and both the IR laser projector and IR detector to be “zeroed” in relationship to the mechanical reticle L24. The pulse generator L36 and control circuit L40 progress through a number of iterations until a constant time delay value is obtained and which is indicative of a valid range measurement. Upon communicating this range measurement information to the microprocessor, an output thereof is communicated to a display driver L47 and which is in turn communicated to a light emitting display L48. Angled mirror L50 redirects the projected light or image from display L48, which is then passed through a display lens L52 and into the prism L28.
Turning now to
Burris Corporation's U.S. Pat. Nos. 8,201,741, 9,091,507 and 9,482,516 describe further refinements in Laser Range Finding (“LRF”) rifle scopes and methods for their use, but all of the foregoing references are less than ideal for actual precision, Long Range marksmanship, because none of them properly account for external ballistic effects actually acting on the bullet, when in flight (including the effects of gyroscopic precession).
None of the above cited references or patents, alone or in combination, adequately address the combined atmospheric and ballistic problems identified by the applicant of the present invention or provide a workable and time-efficient way of developing an accurate firing solution, while in the field. Thus, there is an unmet need for a rapid, accurate and effective rifle sight or projectile weapon aiming system and method for more precisely sensing range to and then estimating a correct point of aim when shooting or engaging targets at long distances, especially in windy conditions.
Accordingly, it is an object of the present invention to overcome the above mentioned difficulties by providing an enhanced system and method for sensing or measuring the range to a selected target and then compensating for a projectile's ballistic behavior while developing a field expedient firing solution, and calculating and displaying a correct point of aim when shooting or engaging targets at long distances. The applicant's initial work was directed to determining an aim point for one specific type of ammunition, and the invention now includes an adaptive method allowing a shooter in the field to adapt to changes in available ammunition and compensate for variations in ammunition or atmospheric conditions.
The applicant has engaged in a rigorous study of precision shooting and external ballistics and observed what initially appeared to be external ballistics anomalies when engaged in carefully controlled experiments in precise shooting at long range. The anomalies were observed to vary with environmental or atmospheric conditions, especially crosswinds. The variations in the anomalies were observed to be repeatable, and so a precise evaluation of the anomalies was undertaken and it was discovered that all of the long range reticles presently employed in the prior art rifle scopes and LRF equipped scopes are essentially wrong.
A refined method and aiming reticle has been developed which allows a more precise estimate of external ballistic behavior for a given projectile when a given set of environmental or atmospheric conditions are observed to be momentarily present. Expressed most plainly, the range finding and aim compensating system and reticle of the present invention differs from prior art long range reticles and LRF equipped scopes in two significant and easily perceived ways:
first, the reticle and system of the present invention is configured to compensate for effects of ALL of the effects gyroscopic precession, including Crosswind Jump, and so the lateral or windage aim point adjustment axes are not horizontal, meaning that they are not simply horizontal straight lines which are perpendicular to a vertical straight line crosshair; and
second, the reticle and system of the present invention is configured to compensate for Dissimilar Wind Drift, and so the arrayed aim point indicators on each windage adjustment axis are not spaced symmetrically about the vertical crosshair, meaning that a given wind speed's full value windage offset indicator on the left side of the vertical crosshair is not spaced from the vertical crosshair at the same lateral distance as the corresponding given wind speed's full value windage offset indicator on the right side of the vertical crosshair.
Apart from the Tubb™ DTAC™ reticle discussed above, the reticles of the prior art have a vertical crosshair or post intended to be seen (through the riflescope) as being exactly perpendicular to a horizontal crosshair that is parallel to the horizon when the rifle is held level with no angular variation from vertical (or “rifle cant”). Those prior art reticles also include a plurality of “secondary horizontal crosshairs” (e.g., 24 in FIG. 2 of Sammut's U.S. Pat. No. 6,453,595). The secondary horizontal crosshairs are typically divided with evenly spaced indicia on both sides of the vertical crosshair (e.g., 26 in FIG. 2 of Sammut's U.S. Pat. No. 6,453,595 or as shown in FIG. 3 of this applicant's U.S. Pat. No. 7,325,353). These prior art reticles represent a prediction of where a bullet will strike a target, and that prior art prediction includes an assumption or estimation that a windage offset to the left is going to be identical to and symmetrical with a windage offset to the right, and that assumption is plainly, provably wrong, for reasons supported in the more arcane technical literature on ballistics and explained below.
Another assumption built into the prior art reticles pertains to the predicted effect on elevation arising from increasing windage adjustments, because the prior art reticles effectively predict that no change in elevation (i.e., holdover) should be made, no matter how much windage adjustment is needed. This second assumption is demonstrated by the fact that the prior art reticles all have straight and parallel “secondary horizontal crosshairs” (e.g., 24 in FIG. 2 of Sammut's U.S. Pat. No. 6,453,595 or as shown in FIG. 3 of this applicant's U.S. Pat. No. 7,325,353), and that assumption is also plainly, provably wrong.
The applicant of the present invention first questioned and then discarded these assumptions, choosing instead to empirically observe, record and plot the actual ballistic performance for a series of carefully controlled shots at selected ranges, and the plotted observations have been used to develop an improved range finding and aim compensating system and method which provides a more accurate predictor of the effects of observed atmospheric and environmental conditions on a bullet's external ballistics, especially at longer ranges. The applicant's discoveries are combined into a LRF and rifle scope system and in the method of the present invention a measured range is used to highlight part of a reticle which provides easy to use and accurate estimations of the external ballistic effects of (a) spin drift, (b) crosswind jump or aeronautical jump and (c) dissimilar wind drift.
The range-finding rifle sight or projectile weapon aiming system of the present invention preferably includes a Laser Range Finder (e.g., “LRF”) equipped rifle scope assembly with a reticle defining an array of aiming dots with a nearly but not exactly vertical array of aiming indicia which intersect a main horizontal crosshair to define a central or primary aiming point. The reticle of the present invention also includes a plurality of nearly horizontal downrange windage adjustment axes arrayed beneath the main horizontal crosshair. The downrange windage adjustment axes are not horizontal lines, meaning that they are not secondary horizontal crosshairs each being perpendicular to a vertical crosshair. Instead, each downrange windage axis defines an angled or sloped array of windage offset adjustment indicia or aim points. If a downrange windage axis line were drawn left to right through all of the windage offset adjustment indicia corresponding to a selected range (e.g., 800 yards), that 800 yard downrange windage axis line would slope downwardly from horizontal at a small angle (e.g., five degrees or greater), for a rifle barrel with right-hand twist rifling and a right-spinning projectile. The range-finding (e.g., LRF) and ballistic effect compensating system of the present invention includes a reticle aim point field and an ammunition adaptive aim compensation method. The range finding and aim compensating system of the present invention includes a ballistic effect compensating reticle with a multiple point elevation and windage aim point field that has a primary aiming mark indicating (a) a primary aiming point adapted to be sighted-in at a first selected range and (b) the locus of the LRF beam for sensing Line of Sight (“LOS”) range 29 to a selected target 28.
The aim point field also includes a plurality of secondary aiming points arrayed beneath the primary aiming mark illustrating aim points for a plurality of crosswind conditions at selected ranges. The method for compensating for a projectile's ballistic behavior while developing a field expedient firing solution permits the shooter to sense or measure the LOS range to target, (29, e.g., corresponding to an adjusted range call of 800 yards), and sense or input the slope angle, local or nominal air density ballistic characteristics and crosswind velocity (e.g., in mph), which is then used to designate an optimum sloped row of downrange windage hold points. The adaptive method allows a shooter in the field to adapt to changes in available ammunition (e.g., when changing from M118LR ammo to M80 ammo) and compensate for variations in ammunition as well as changes in atmospheric conditions.
In the range finding and aim compensating system and method of the present invention, the windage offset adjustment indicia (or wind dots) on each sloped downrange wind dot line are not symmetrical about the vertical crosshair, meaning that for a given crosswind speed (e.g., 5 mph) the selected windage offset adjustment indicator or wind dot on the left side of the vertical crosshair is not spaced from the vertical crosshair at the same lateral distance as the corresponding windage offset adjustment indicator on the right side of the vertical crosshair. Instead, the reticle and method of the present invention define differing windage offsets for (a) wind from the left and (b) wind from the right. Those windage offsets refer to an elevation adjustment axis which diverges laterally from the vertical crosshair. The elevation adjustment axis defines the diverging array of elevation offset adjustment indicia for selected ranges (e.g., 300 to 1600 yards, in 100 yard increments). An elevation offset adjustment axis line could be drawn through all of the elevation offset adjustment indicia (corresponding to no wind) to define only the predicted effect of spin drift and precession, as described in this applicant's U.S. Pat. No. 7,325,353 (which is incorporated herein by reference).
In accordance with the present invention, a range finding and aim compensating system and aiming method are provided to account for the previously ill-defined effects of the newly observed interaction between ballistic and atmospheric effects. Careful research of technical journals was used to find reports of identified effects in disparate sources, but those effects were never addressed in a comprehensive system to provide a range finding and aim compensating system and aiming solution or estimating method which can be easily and quickly used by a marksman in the field.
The traditional range-finding (e.g., LRF) system or scope (e.g. L12 of
The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of a specific embodiment thereof, particularly when taken in conjunction with the accompanying drawings, wherein like reference numerals in the various figures are utilized to designate like components.
In order to provide context for the present invention, please refer again to Prior Art
While an exemplary variable power LRF equipped scope 804 (see, e.g.,
Turning next to
Range-finding component subassembly 816 may be a near infrared laser projector consisting of a pulsed laser diode 834 in communication with the collimating lens 832, again mounted in an aligned or adjacent fashion relative to the objective lens 830 of the erect image telescope 804 to produce a small spot of light (e.g., at a range of 1000 yards or more). Range-finding component subassembly 816 is aligned or connected to scope body 814 and is shown in dashed lines in
Returning to the exemplary embodiment of
In the illustrated example, LRF scope system 811 includes circuitry connected and responsive to a laser or IR detector (not shown) located in proximity to the prism 828 and communicating with control circuit 840. The laser or IR detector (not shown) is preferably capable of being illuminated through the scope's objective lens 830, so both the laser projector and the laser or IR detector are “zeroed” in relationship to the DTR™ reticle 824. The laser generator 836 and control circuit 840, in operation, progress through a number of pulse timing iterations until a constant time delay value is obtained and which is indicative of a valid range measurement (in a known manner). Upon communicating this range measurement information to the microprocessor 838, an output thereof is communicated to a display driver 847 and which is in turn communicated to a light emitting display 848. Angled mirror 850 redirects the projected light or image from display 848, which is then passed through a display lens 852 and into prism 828 in response to an Effective Hold Point (“EHP”) range calculation undertaken in response to a program which controls microprocessor 838. In a preferred embodiment, the EHP range is displayed numerically in the reticle image for the user (e.g., “800 YDS” as seen in
While variable power scopes typically include two focal planes, the reticle screen or glass (e.g. 16 or 824) used in connection with the reticles of the present invention (e.g., with aim point fields 150, 350 or 650) is preferably positioned at the first or front focal plane (“FP1”) between the distal objective lens (e.g. 12 or 830) and the erector lens (e.g. 18 (or 822 as seen in
As noted above, the applicant's prior art DTAC™ reticles (e.g., as shown in
Referring next to
The system 810, reticle (e.g., with aim point fields 150, 350 or 650) and method of present invention as illustrated in
The range finding and aim compensating system 810 and method of present invention as illustrated in
The sloped downrange wind dots in aim point field 150 (e.g., for 800 yards, along sloped row 160A) have been configured or plotted to aid the shooter by illustrating the inter-relationship of the external ballistic effects observed and recorded by the applicant as part of the development work for the system and method of the present invention. In reticle aim point field 150, the windage aim point indicia or laterally offset wind dots on each sloped array of wind dots are not symmetrical about the vertical reference line 156, meaning that a full value windage offset indicator (e.g. 5 mph) on the left side of vertical crosshair 156 is not spaced from vertical crosshair 156 at the same distance as the corresponding full value windage offset indicator (e.g. 5 mph) on the right side of the vertical crosshair, for a given wind velocity offset.
As noted above, the LRF scope reticles of the prior art (e.g., as illustrated in
The applicant of the present invention re-examined these assumptions and empirically observed, recorded and plotted the actual ballistic performance for a series of carefully controlled shots at selected ranges, and the plotted observations have been used to develop improved reticle aim point field (e.g., 150) which has been demonstrated to be a more accurate predictor of the effects of atmospheric and environmental conditions on a bullet's flight.
Experimental Approach and Prototype Development:
As noted above the reticle systems (e.g., 200, 300 and 600) and the method of the present invention are useful to predict the performance of specific ammunition fired from a specific rifle system (e.g., 6), but can be used with a range of other ammunition by using pre-defined correction criteria. The data for the reticle aim point field 150 shown in
The range finding and aim compensating system of the present invention (e.g., 804) preferably includes an aim point field (e.g., 150) with a vertical crosshair 156 and a horizontal crosshair 152 which intersect at a right angle and also includes a plurality of windage adjustment axes (e.g., 160A) arrayed beneath horizontal crosshair 152. The windage adjustment axes (e.g., 160A) are angled downwardly at a shallow angle (e.g., five degrees, for RH twist), meaning that they are not secondary horizontal crosshairs each being perpendicular to the vertical crosshair 156. Instead, each windage axis defines an angled or sloped array of windage offset adjustment indicia. If a windage axis line were drawn through all of the windage offset adjustment indicia corresponding to a selected range (e.g., 800 yards), that windage axis line would slope downwardly from horizontal at a small angle (e.g., five degrees), as illustrated in
As noted above, the windage offset adjustment indicia on each windage adjustment axis are not symmetrical about the vertical crosshair 156 or symmetrical around the array of elevation indicia or nearly vertical central aiming dot line 154. The nearly vertical central aiming dot line 154 provides a “no wind zero” for selected ranges (e.g., 100 to more than 1500 yards, as seen in
The phenomena or external ballistic effects observed by the applicant are not anticipated in the prior art for rifle scopes, but applicant's research into the scientific literature has provided some interesting insights. A scientific text entitled “Rifle Accuracy Facts” by H. R. Vaughn, and at pages 195-197, describes a correlation between gyroscopic stability and wind drift. An excerpt from another scientific text entitled “Modern Exterior Ballistics” by R. L. McCoy (with appended errata published after the author's death), at pages 267-272, describes a USAF scientific inquiry into what was called “Aerodynamic Jump” due to crosswind and experiments in aircraft. Applicant's experiments have been evaluated in light of this literature and, as a result, applicant has developed a model for two external ballistics mechanisms which appear to be at work. The first mechanism is now characterized, for purposes of the system and method of the present invention, as “Crosswind Jump” wherein the elevation-hold or adjustment direction (up or down) varies, depending on whether the shooter is compensating for left crosswind (270°) or right crosswind (90°), and the present invention's adaptation to these effects is illustrated in
The second mechanism (dubbed “Dissimilar Wind Drift” for purposes of the system and method of the present invention) was observed as notably distinct lateral offsets for windage, depending on whether a crosswind was observed as left wind (270°) or right wind (90°). Referring again to
Applicant's reticle system (e.g., 200, 300 or 600) permits the user or shooter to quickly align range finding and aim compensating system 810 toward a target of interest 28 (e.g., as shown in
The range finding and aim compensating scope 804 and reticle of the present invention can be used with the popular M118LR 0.308 (or 7.62NATO) caliber ammunition which is typically provides a muzzle velocity of 2565 FPS. Turning now to
As noted above, the nearly but not exactly vertical central aiming dot line 354 is curved or skewed somewhat to the right of the true vertical reference line 356 to compensate for “spin drift” of a spin-stabilized bullet or projectile in its trajectory when there is no significant crosswind. The exemplary M24 or M40 variant rifle barrels (e.g., 7) have “right twist” inwardly projecting rifling which spirals to the right, or clockwise, from the proximal chamber to the distal muzzle of the barrel. The rifling (e.g., in barrel 7) engraves and imparts a corresponding clockwise stabilizing spin to the M118LR bullet (not shown). As the projectile or bullet travels an arcuate trajectory in its distal or down range ballistic flight between the muzzle and the target, the longitudinal axis of the bullet will deflect angularly to follow that arcuate trajectory. As noted above, the flying bullet's clockwise spin results in gyroscopic precession which generates a force that is transverse or normal (i.e., ninety degrees) to the arcuate trajectory, causing the bullet to deflect to the right. This effect is seen most clearly at relatively long ranges, where there is substantial arc to the trajectory of the bullet (e.g., as illustrated in
In
The nearly vertical columns 362A, 362B, 364A, 364B, etc., spread as they extend downwardly to greater and greater ranges, but not symmetrically, due to the external ballistics factors including Crosswind Jump and Dissimilar Crosswind Drift, as discussed above. These nearly vertical columns define aligned angled columns or axes of aim points configured to provide an aiming aid permitting the shooter to compensate for windage, i.e. the lateral drift of a bullet due to any crosswind component. As noted above, downrange crosswinds will have an ever greater effect upon the path of a bullet with longer ranges. Accordingly, the vertical columns spread wider, laterally, at greater ranges or distances, with the two inner columns 362A and 364A being closest to the column of central aiming dots 354 and being spaced to provide correction for a five mile per hour crosswind component, the next two adjacent columns 362B, 364B providing correction for a ten mile per hour crosswind component, etc.
In addition, a moving target must be provided with a “lead,” somewhat analogous to the lateral correction required for windage. The present scope reticle includes approximate lead indicators 366B (for slower walking speed, indicated by the “W”) and 366A (farther from the central aim point 358 for running targets, indicated by the “R”). These lead indicators 366A and 366B are approximate, with the exact lead depending upon the velocity component of the target normal to the bullet trajectory and the distance of the target from the shooter's position.
As noted above, in order to use the elevation and windage aim point field 350 of
It should be noted that each of the stadia markings 402 and 404 comprises a small triangular shape, rather than a circular dot or the like, as is conventional in scope reticle markings. The polygonal stadia markings of the present system place one linear side of the polygon (preferably a relatively flat triangle) normal to the axis of the stadia markings, e.g. the horizontal crosshair 352. This provides a precise, specific alignment line, i.e. the base of the triangular mark, for alignment with the right end or the bottom of the target or adjacent object, depending upon whether the length or the height of the object is being ranged. Conventional round circles or dots are subject to different procedures by different shooters, with some shooters aligning the base or end of the object with the center of the dot, as they would with the sighting field, and others aligning the edge of the object with one side of the dot. It will be apparent that this can lead to errors in subtended angle estimation, and therefore in estimating the distance to the target.
Referring back to
Range finding and aim compensating rifle scope 804 when equipped with aim compensating reticle 300 of
DA represents “Density Altitude” and variations in ammunition velocity can be integrated into the aim point correction method (preprogrammed into memory accessible by microprocessor 838) by selecting a lower or higher DA correction number, and this part of the applicant's method referred to as “DA Adaptability”. This means that a family of reticles is readily made available for a number of different bullets for use with range finding and aim compensating scope 804. This particular example is for the USGI M118LR ammunition, which is a 0.308, 175 gr. Sierra™ Match King™ bullet, modeled for use with a rifle having scope 2.5 inches over bore centerline and a 100 yard zero. In computing the optimum EHP range, the bullet's flight path is defined to match the reticle at the following combinations of muzzle velocities and air densities:
2 k DA=2625 FPS and 43.8 MOA at 1100 yards
3 k DA=2600 FPS and 43.8 MOA at 1100 yards
4 k DA=2565 FPS and 43.6 MOA at 1100 yards
5 k DA=2550 FPS and 43.7 MOA at 1100 yards
6 k DA=2525 FPS and 43.7 MOA at 1100 yards
where 1100 yard come-ups were used since this bullet is still above the transonic region. Thus, the reticle's density correction graphic indicia array 500 can be used with Density Altitude Graph 550 (or a corresponding Look Up Table programmed into scope 804) to provide the user with a convenient method to adjust or correct the selected aim point for a given firing solution when firing using different types of ammunition or in varying atmospheric conditions with varying air densities.
In accordance with the method and system (e.g., 810) of the present invention, each user is preferably provided with information (e.g., a placard or card for each scope 804 which defines the bullet path values (come-ups) at selected (e.g., 100 yard) intervals. When the user sets up their rifle system (and programs scope 804), they chronograph their rifle and pick the Density Altitude which matches the system's (i.e., rifle+ammunition) velocity. Handloaders have the option of loading to that velocity to match the main reticle value. The conditions which result in a bullet path that matches the reticle is referred to throughout this as the “nominal” or “main” conditions. The scope legend (e.g., 326), viewed by zooming back to the minimum magnification, shows the model and revision number of the reticle from which can be determined the main conditions which match the reticle.
Experienced long range marksmen and persons having skill in the art of external ballistics as applied to long range precision shooting will recognize that the present invention makes available a novel range finding and aim compensating system (e.g., 810) and ballistic effect compensating reticle system (e.g., 200, 300 or 600) for use in a projectile weapon aiming system adapted to provide a field expedient firing solution for a selected projectile, comprising: (a) a multiple point elevation and windage aim point field (e.g., 150, 350 or 650) including a primary aiming mark (e.g., 158, 358 or 658) indicating a primary aiming point adapted to be sighted-in at a first selected range (e.g., 200 yards); (b) the aim point field including a nearly vertical array of secondary aiming marks (e.g., 154, 354 or 654) spaced progressively increasing incremental distances below the primary aiming point and indicating corresponding secondary aiming points along a curving, nearly vertical axis intersecting the primary aiming mark, the secondary aiming points positioned to compensate for ballistic drop at preselected regular incremental ranges beyond the first selected range for the selected projectile having pre-defined ballistic characteristics where the aim point field, as displayed, also includes a sloped wind dot array or downrange array of windage aiming marks spaced apart along a secondary non-horizontal axes (e.g., 160A) intersecting a first selected secondary aiming point (e.g., corresponding to a selected EHP range). The first array of windage aiming marks includes a first windage aiming mark spaced apart to the left of the vertical axis at a first windage offset distance from the vertical axis selected to compensate for right-to-left crosswind of a preselected first incremental velocity (e.g., 5 mph) at the range of said first selected secondary aiming point, and a second windage aiming mark spaced apart to the right of the vertical axis at a second windage offset distance from the vertical axis selected to compensate for left-to-right crosswind of that same preselected first incremental velocity (e.g., 5 mph) at said range of said first selected secondary aiming point. The first array of windage aiming marks defining the highlighted or displayed sloped row of windage aiming points (e.g., as best seen in
In the illustrated embodiments, the range finding and aim compensating scope 804 has a ballistic effect compensating reticle (e.g., 200, 300 or 600) with several sloped arrays of windage aiming marks which define sloped rows of windage aiming points having a negative slope which is a function of the right-hand spin direction for the projectile's stabilizing spin or a rifle barrel's right-hand twist rifling, thus compensating for the projectile's gyroscopic precession effects (including crosswind jump and dissimilar wind drift) and providing a more accurate compensated aim point for any range for which the projectile remains supersonic.
The ballistic effect compensating reticle (e.g., 200, 300 or 600) has each secondary aiming point intersected by a secondary array of windage aiming marks (e.g., 360E, for 300 yds) defining the sloped row of windage aiming points having a slope which is a function of the direction and velocity of the projectile's stabilizing spin or a rifle barrel's rifling twist rate and direction, and that sloped row of windage aiming points are spaced laterally in increments selected to indicate crosswind speed intervals (e.g., 5 mph). In the range finding and aim compensating system 810 and the method of the present invention, aiming compensation for ballistics and windage for multiple preselected incremental crosswind velocities (e.g., 5, 10, 15, 20 and 25 mph) is sensed during a first LRF display mode, and then calculated and displayed during a second shooting display mode. In the illustrated embodiments, each sloped row of windage aiming points includes windage aiming marks positioned to compensate for leftward and rightward crosswinds of 10 miles per hour and 20 miles per hour at the range of the secondary aiming point corresponding to the sloped row of windage aiming points, and at least one of the sloped row of windage aiming points is bounded by laterally spaced distance indicators which, in the method of the present invention, are illuminated or designated in the reticle to show the shooter the closest row to that indicated from the LRF sensing step. So, for example, if the range to target 29 is for a range which corresponds to an EHP that falls between two sloped rows (e.g., if EHP is calculated to be between 800 yds and 850 yds, e.g., 825 yds, as shown in
Using the DA adaptability numbers illustrated in
NAV−Current DA×ADC #=Delta Yard (Eq. 1)
And EHP is then calculated as:
EHP=LOS range−Delta Yard (Eq. 2)
So referring again to
The method for calculating the adjusted optimum Effective Hold Point (“EHP”) for display in EHP display window 862 and for choosing which sloped row of wind dot lines to illuminate (when in shooting display mode) is illustrated in the process flow diagram of
For reticles with aim point fields such as 150, 350 or 650, the reticle's permanently inscribed pattern of wind dots is always visible, and in scope 804 microprocessor 838 is programmed to Illuminate or designate the one sloped wind dot line array which most closely matches the stored EHP value. Optionally, as illustrated in diagram block 910, Optional if LOS range is under a first selected threshold range (e.g., 500 yds) and optimum EHP range is within a selected percentage (e.g. 10%) or a selected distance (e.g., 10 yards) of the one closest sloped row of wind dots illuminated, the controller can be programmed to illuminate ONLY the closest sloped row; however, if this condition is NOT true, then the scope 804 is programmed to surround or bracket the true aim point EHP by illuminating both the closest row of sloped wind dots AND the second closest sloped row. Alternatively, where the reticles (200, 300 or 600) exist only in software within scope 804, and are NOT permanently etched on a reticle surface 824, the microprocessor is programmed to display only one sloped row at exactly the EHP.
Preferably, at least one of the sloped arrays windage aiming points is proximate an air density or projectile ballistic characteristic adjustment indicator such as the “Lazy” DA adjustment factors arrayed in density correction indicia array 670, and the air density or projectile ballistic characteristic adjustment indicator is preferably a Density Altitude (DA) correction indicator, but could also be expressed in air density units known with the acronym “DU.” Those density correction factors can also be used by the shooter “on the fly”, in case it is not possible to input current DA information to microprocessor 838.
Generally, when using the range-finding and compensating scope 804 with a ballistic effect compensating reticle aimpoint field (e.g., 150, 350 or 650), if there is actually no crosswind, the nearly vertical array of secondary aiming marks (e.g., 154, 354 or 654) provide very clearly defined secondary aiming points along a curving, nearly vertical axis and are curved in a direction that is a function of the direction of the projectile's stabilizing spin from rifle the barrel (e.g., 7) rifling direction, thus compensating for spin drift at any sensed EHP range. The primary aiming mark (e.g., 358) formed by the intersection of the primary horizontal sight line (e.g., 352) and the nearly vertical array of secondary aiming marks provide a conspicuous indicator or “dot” which may be illuminated or highlighted during the LRF sensing step, while LRF-DTR scope 804 is operating in the LRF display mode, during which the shooter aims rifle system 810 so that the primary aiming mark (e.g., 158, 358 or 658) is aligned directly over or at the target surface. The main horizontal crosshair array (e.g., 152, 352 or 652) preferably includes a bold, widened portion (370L and 370R) located radially outward from the primary aiming point, the widened portion having an innermost pointed end located proximal of the primary aiming point which provides an aid when aiming the LRF for LOS range detection.
The range-finding and ballistic effect compensating system 810 is shown with exemplary reticle aim point field (e.g., 150, 350 or 650) which preferably also includes at least a second array of windage aiming marks spaced apart along a second non-horizontal axis intersecting a second selected secondary aiming point; and the second array of windage aiming marks includes a third windage aiming mark spaced apart to the left of the vertical axis at a third windage offset distance from the vertical axis selected to compensate for right-to-left crosswind of the preselected first incremental velocity (e.g., 10 mph) at the range of said second selected secondary aiming point (e.g., 800 yards), and a fourth windage aiming mark spaced apart to the right of the vertical axis at a fourth windage offset distance from the vertical axis selected to compensate for left-to-right crosswind of the same preselected first incremental velocity at the same range, and the second array of windage aiming marks define another sloped row of windage aiming points having a slope which is also a function of the direction and velocity of said projectile's stabilizing spin or a rifle barrel's rifling twist rate and direction, thus compensating for the projectile's crosswind jump. In addition, the ballistic effect compensating reticle's aim point field also includes a third array of windage aiming marks spaced apart along a third non-horizontal axis intersecting a third selected secondary aiming point, where the third array of windage aiming marks includes a fifth windage aiming mark spaced apart to the left of the vertical axis at a fifth windage offset distance from the vertical axis selected to compensate for right-to-left crosswind of the preselected first incremental velocity at the range of said third selected secondary aiming point, and a sixth windage aiming mark spaced apart to the right of the vertical axis at a sixth windage offset distance from the vertical axis selected to compensate for left-to-right crosswind of said preselected first incremental velocity at said range of said third selected secondary aiming point; herein said second array of windage aiming marks define another sloped row of windage aiming points having a slope which is also a function of the direction and velocity of said projectile's stabilizing spin or a rifle barrel's rifling twist rate and direction, thus compensating for crosswind jump.
The range-finding and ballistic effect compensating system 810 reticle (e.g., 200, 300 or 600) may also have the aim point field's first array of windage aiming marks spaced apart along the second non-horizontal axis to include a third windage aiming mark spaced apart to the left of the vertical axis at a third windage offset distance from the first windage aiming mark selected to compensate for right-to-left crosswind of twice the preselected first incremental velocity at the range of said second selected secondary aiming point, and have a fourth windage aiming mark spaced apart to the right of the vertical axis at a fourth windage offset distance from the second windage aiming mark selected to compensate for left-to-right crosswind of twice said preselected first incremental velocity at said range of said selected secondary aiming point. Thus the third windage offset distance is greater than or lesser than the fourth windage offset distance, where the windage offset distances are a function of or are determined by the direction and velocity of the projectile's stabilizing spin or a rifle barrel's rifling twist rate and direction, thus compensating for the projectile's Dissimilar Wind Drift. The ballistic effect compensating reticle has the third windage offset distance configured to be greater than the fourth windage offset distance, and the windage offset distances are a function of or are determined by the projectile's right hand stabilizing spin or a rifle barrel's rifling right-twist direction, thus compensating for said projectile's Dissimilar Wind Drift.
Broadly speaking, the range finding and aim compensating system's reticle (e.g., 200, 300 or 600) has an aim point field configured to compensate for the selected projectile's ballistic behavior while developing a field expedient firing solution expressed two-dimensional terms of:
(a) EHP range or distance, used to orient a field expedient aim point vertically among the secondary aiming marks in said vertical array, and
(b) crosswind relative velocity, used to orient the aim point laterally among a selected array of windage hold points.
The range-finding and ballistic effect compensating method for use when firing a selected projectile from a selected rifle or projectile weapon (e.g., 6 or 810) and developing a field expedient firing solution, comprises: (a) providing a range-finding and ballistic effect compensating system 810 with a ballistic effect compensating reticle system (e.g., 200, 300 or 600) comprising a multiple point elevation and windage aim point field (e.g., 150, 350 or 650) including a primary aiming mark (e.g., 158, 358 or 658) intersecting a nearly vertical array of secondary aiming marks spaced along a curving, nearly vertical axis, where the secondary aiming points are positioned to compensate for ballistic drop at preselected regular incremental ranges (e.g., every 25 yards or every 50 yards) beyond the first selected range for the selected projectile having pre-defined ballistic characteristics; and where the aim point field also includes a sloped row of wind dots or array of windage aiming marks spaced apart along a secondary non-horizontal axis intersecting that first selected secondary aiming point; wherein the sloped row of wind dots define a sloped row of windage aiming points having a slope which is a function of the direction and velocity of said projectile's stabilizing spin or a rifle barrel's rifling twist rate and direction, thus compensating for said projectile's crosswind jump; (b) based on at least the selected projectile, identifying said projectile's associated nominal Air Density ballistic characteristics; (c) sensing a LOS range to a target, based on the range to the target and the nominal air density ballistic characteristics of the selected projectile, determining a yardage equivalent aiming adjustment (or EHP) for the projectile weapon 810; (d) illuminating or displaying at least one sloped row of wind dots arrayed at a range corresponding to the sensed EHP and then evaluating the actual wind between the shooter and the target to then determine a windage hold point along that illuminated sloped row (based on any crosswind sensed or perceived), and then aiming the rifle or projectile weapon 810 using the yardage equivalent EHP aiming adjustment for elevation hold-off and holding laterally for the selected windage hold point.
The range-finding and ballistic effect aim compensation method of the present invention includes providing ballistic compensation information as a function of and indexed according to an atmospheric condition such as density altitude (“DA”) for presentation to the shooter or user, and then associating that ballistic compensation information with the firearm scope reticle feature (e.g., the “lazy 7” at 800 yds from indicia array 670 in
The range-finding and ballistic effect compensating system 810 is readily configured to adjust the point of aim of a projectile firing weapon or instrument firing a selected projectile under varying atmospheric and wind conditions (e.g. with a reticle such as 200, 300 or 600) and preferably includes a plurality of aiming points disposed upon that reticle, where a plurality of aiming points positioned for proper aim at various predetermined range-distances and wind conditions include at least a first array of windage aiming marks spaced apart along a non-horizontal axis (e.g., array 360-0 for 800 yards) to define the sloped row of windage aiming points having a slope which is a function of the direction and velocity of the selected projectile's stabilizing spin or a rifle barrel's rifling twist rate and direction, thus compensating for said selected projectile's crosswind jump; and where all of said predetermined range-distances and wind conditions are based upon a baseline atmospheric condition such as an expected air density. The range-finding and ballistic effect compensating system 810 optionally includes a means for determining existing density altitude characteristics (such as DA graph 550 in
Preferably, the range-finding and ballistic effect compensating system's information is pre-programmed into the scope's memory, but may also be input via data interface 843 in a manner which mirrors or is consistent with the data encoded into the plurality of aiming points disposed upon the reticle (e.g. 200, 300 or 600), as best seen in
As noted above, the applicant's initial work was directed to determining an aim point for one specific type of ammunition, and the invention now includes a range-finding and ballistic effect compensating system 810 for using an adaptive method allowing a shooter in the field to adapt to changes in available ammunition and compensate for variations in ammunition or atmospheric conditions. Illustrative examples are provided in
So, for example, if a shooter's rifle (e.g., 6 or 810) is set up to shoot M118LR ammunition (i.e., with the 0.308 dia. 175 gr Sierra™ Match King™ HPBT projectile) at an initial muzzle velocity of 2565 Ft./Sec., the rifle may be assigned a nominal DA baseline or index value of 4 KDA (e.g., as shown and described in
The ammunition-change adaptive range-finding and ballistic effect aim compensation method for use when firing first and second selected projectiles from a selected rifle or projectile weapon (e.g., 4 or 810) and developing a displayed field expedient firing solution (as a selected sloped row of windage dots) thus comprises: (a) providing a range-finding and ballistic effect compensating system 810 with a ballistic effect compensating reticle system (e.g., 200, 300 or 600) comprising a multiple point elevation and windage aim point field (e.g., 150, 350 or 650) including a primary aiming mark (e.g., 158, 358 or 658) intersecting a nearly vertical array of secondary aiming marks spaced along a curving, nearly vertical axis, the secondary aiming points positioned to compensate for ballistic drop at preselected regular incremental ranges beyond the first selected range for the selected projectile having pre-defined ballistic characteristics; and said aim point field also including a first array of windage aiming marks spaced apart along a secondary non-horizontal axis intersecting a first selected secondary aiming point; wherein said first array of windage aiming marks define a sloped row of windage aiming points having a slope which is a function of the direction and velocity of said first or second projectile's stabilizing spin or the rifle barrel's rifling twist rate and direction, thus compensating for said first or second projectile's crosswind jump; (b) based on at least the first selected projectile (e.g., M118LR ammunition (i.e., with the 0.308 dia. 175 gr Sierra™ Matchking™ HPBT projectile at an initial muzzle velocity of 2565 Ft./Sec.), identifying said first or projectile's associated nominal Air Density ballistic characteristics (e.g., 4 kDA); (c) sensing a LOS range to a target, based on the range to the target and the nominal air density ballistic characteristics of the first or second selected projectile, determining a yardage equivalent aiming adjustment or EHP for the projectile weapon and displaying, illuminating of highlighting one or two sloped wind dot lines corresponding to or bracketing the EHP range (d) determining a windage hold point, based on any crosswind sensed or perceived, and (e) aiming the rifle or projectile weapon using the displayed EHP yardage equivalent derived sloped row of windage aiming dots (e.g., for 800 yds when EHP is 800 yds) for elevation hold-off and choosing one or more of the wind dots in the sloped wind dot array to estimate the optimum windage hold point.
Having described preferred embodiments of a new and improved reticle and method, it is believed that other modifications, variations and changes will be suggested to those skilled in the art in view of the teachings set forth herein. It is therefore to be understood that all such variations, modifications and changes are believed to fall within the scope of the present invention as set forth in the following claims.
This application is related to and claims priority from: (1) commonly owned U.S. provisional patent application No. 62/650,602, filed Mar. 30, 2018, (2) and is also a continuation in part of commonly owned U.S. non-provisional patent application Ser. No. 16/253,169, filed Jan. 21, 2019, which is a continuation of (3) Ser. No. 15/224,646 filed Jul. 31, 2016, now patented (U.S. Pat. No. 10,184,752) which claims Priority from (4) Provisional Application 62/274,054, filed Dec. 31, 2015, and (5) Provisional Application 62/199,139, filed Jul. 30, 2015, (6) and is also a continuation in part of commonly owned U.S. non-provisional patent application Ser. No. 15/419,793, filed Jan. 30, 2017, which is a continuation of (7) Ser. No. 14/216,674, filed Mar. 17, 2014, now patented (U.S. Pat. No. 9,581,415) which is a continuation of (8) Ser. No. 13/947,858, filed Jul. 22, 2013, now patented (U.S. Pat. No. 9,557,142) which is a continuation of (9) Ser. No. 13/342,197, filed Jan. 2, 2012, now patented (U.S. Pat. No. 8,701,330) which claims Priority from (10) Provisional Application 61/437,990, filed Jan. 31, 2011, and (11) Provisional Application 61/429,128, filed Jan. 1, 2011, the entire disclosures of which are all incorporated herein by reference.
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| Number | Date | Country | |
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| 20200018566 A1 | Jan 2020 | US |
| Number | Date | Country | |
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| 62650602 | Mar 2018 | US | |
| 61437990 | Jan 2011 | US | |
| 61429128 | Jan 2011 | US |
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| Parent | 13342197 | Jan 2012 | US |
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