BACKGROUND
The present invention relates to a buffer assembly for a firearm. The buffer assembly includes at least one magnet that offsets an inertial event that occurs during the firing action of a firearm.
SUMMARY
[RECITE CLAIMS IN PARAGRAPH FORM—TO BE ADDED AFTER DRAFT IS FINALIZED]
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates an exemplary firearm including an embodiment of the present invention.
FIG. 2 is an exploded view of a lower receiver assembly of the firearm, including a buffer assembly having a buffer.
FIG. 3 is an exploded view of an upper receiver assembly of the firearm and a bolt carrier.
FIG. 4A is a cross-sectional view of a first embodiment of the buffer in an at-rest condition.
FIG. 4B is a cross-sectional view of the first embodiment of the buffer in a dead-blow condition.
FIG. 5A is a cross-sectional view of a second embodiment of the buffer in an at-rest condition.
FIG. 5B is a cross-sectional view of the second embodiment of the buffer in a dead-blow condition.
FIG. 6 is a cross-sectional view of a third embodiment of the buffer in an at-rest condition.
FIG. 7 is a cross-sectional view of a fourth embodiment of the buffer in an at-rest condition.
FIG. 8A is a cross-sectional view of a fifth embodiment of the buffer in an at-rest condition.
FIG. 8B is a cross-sectional view of the fifth embodiment of the buffer in a dead-blow condition.
FIG. 9A is a cross-sectional view of a sixth embodiment of the buffer in a forward-directed dead-blow condition.
FIG. 9B is a cross-sectional view of the sixth embodiment of the buffer in a rearward-directed dead-blow condition.
FIG. 10A is a cross-sectional view of a seventh embodiment of the buffer in an at-rest condition.
FIG. 10B is a cross-sectional view of the seventh embodiment of the buffer in a rearward-directed dead-blow condition.
FIG. 10C is a cross-sectional view of the seventh embodiment of the buffer in a forward-directed dead-blow condition.
DETAILED DESCRIPTION
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.
FIG. 1 illustrates an exemplary firearm 100 which may embody the present invention. For the purposes of this disclosure, directional and relative terms such as front, forward, rear, and rearward are used from the perspective of a firearm operator using the firearm 100 in its intended way. The illustrated firearm 100 is an AR-15 rifle and includes an upper receiver assembly 110 to which a barrel 120, hand guard 130, lower receiver 140, and buttstock 160 are mounted. The components are generally conventional and well known. A buffer assembly 210 is mounted to the lower receiver 140 and extends into the buttstock 160.
FIG. 2 illustrates the buffer assembly 210, which includes a buffer tube 220, an action spring 230, and a buffer 240. The buffer tube 220 includes an open front end 220a, a closed rear end 220b, and a longitudinally-extending internal space 220c. The open front end 220a of the buffer tube 220 is mounted to the rear of the lower receiver 140 with a castle nut 250 and a receiver end plate 260. The buffer tube 220 extends rearwardly from the lower receiver 140 into the buttstock 160. The action spring 230 is a coil compression spring having a front end 230a and a rear end 230b.
The buffer 240 includes a cylindrical buffer body 270, a front end cap 280, and a rear end cap 290. The buffer body 270 includes a front end 270a and a rear end 270b. The front end cap 280 may be threaded onto the front end 270a of cylindrical buffer body 270, permanently affixed to the buffer body 270, or integrally formed with the buffer body 270. The front end cap 280 is of wider diameter than the buffer body 270 to define a shoulder 300. The rear end cap 290 is made of a resilient material such as urethane to cushion the impact of the buffer 240 on the rear end 220b of the internal space 220c of the buffer tube 220 when the buffer 240 is driven rearward as part of the firearm's firing and reloading action. A retaining pin or roll pin 310 secures the rear end cap 290 to the buffer body 270.
The action spring 230 and buffer 240 are inserted through the open front end 220a of the buffer tube 220 into the internal space 220c. The rear end 230b of the action spring 230 bottoms out in and abuts against the closed rear end 220b of internal space 220c of the buffer tube 220. The buffer body 270 is surrounded by the coils of the action spring 230. The front end 230a of the action spring 230 abuts the shoulder 300 of the front end cap 280. The action spring 230 and buffer 240 are retained in the buffer tube 220 with a buffer retaining pin 340 in the lower receiver 140. The buffer retaining pin 340 is spring biased and can be manually deflected into the lower receiver 140 to provide clearance for insertion of the action spring 230 and buffer 240. When released from its deflected condition, the buffer retaining pin 340 extends to trap the action spring 230 and buffer 240 in the buffer tube 220.
FIG. 3 illustrates a bolt carrier 215. The bolt carrier 215 is engaged with the front end cap 280 of the buffer 240 and reciprocates in the upper receiver 110 as part of the firing action of the firearm 100. The bolt carrier 215 is in a battery condition when fully forward in the upper receiver 110 and locked with respect to the barrel 120. The firearm 100 may be fired when in the battery condition, which drives a bullet out of the barrel 120 under the influence of rapidly expanding barrel gases. The barrel gases are recycled from the barrel 120 to drive the bolt carrier 215, and thereby the buffer 240, rearward. This can be done by either directly impinging the barrel gases rearwardly on the bolt carrier 215 or by driving a piston rearwardly under the influence of the barrel gases to strike the bolt carrier 215. In any event, the barrel gases are the motive force for the rearward motion (called a rearward stroke) of the bolt carrier 215. During the rearward stroke, a spent shell from the just-fired round is ejected through a side door of the upper receiver 110 and the action spring 230 is compressed in the buffer tube 220. The rearward stroke ends when the rear end cap 290 bottoms out against the rear end 220b of the buffer tube 220.
A forward stroke commences under the influence of the action spring 230. During the forward stroke, the action spring 230 drives the buffer 240 and bolt carrier 215 forward. The bolt carrier 215 collects a new round from a magazine under the upper receiver 110 and drives the new round into the battery condition. The forward stroke ends when the bolt carrier 215 is in the battery condition, ready to fire the new round.
The present invention relates to a dead-blow mechanism inside the buffer body 270, and more specifically to a magnetic dead-blow biasing mechanism 460 which is part of the dead-blow mechanism. As will be discussed in more detail below, the dead-blow mechanism has two conditions: an at-rest condition and a dead-blow condition. The dead-blow biasing mechanism 460 biases the dead-blow mechanism into the at-rest condition. The dead-blow condition is achieved by overcoming the biasing force of the dead-blow biasing mechanism 460 in response to an inertial event. The purposes of the dead-blow mechanism in the buffer body 270 is to reduce bounce of the bolt carrier 215 or slow down acceleration of the bolt carrier 215 at the beginning or end of the rearward stroke or the beginning or end of the forward stroke, when inertial events occur. Reducing bounce and slowing down acceleration can improve shooting accuracy and optimize the timing of the firing action, as will be described in more detail below.
FIGS. 4A-10C illustrate various configurations (referred to as “embodiments” herein) of an internal assembly 410, 510, 610, 710, 810, 910, 1010 of the buffer 240. The internal assembly 410, 510, 610, 710, 910, 1010 is received in a buffer cavity 270c inside the buffer body 270. Each internal assembly 410, 510, 610, 710, 810, 910, 1010 includes a plurality of conventional masses (referred to as “weights” herein) 420, 421 and conventional resilient spacers 430. In the illustrated embodiments, the spacers 430 are rubber. The plurality of conventional weights 420, 421 includes a forwardmost weight (421f or 420f) and a rearmost weight (421r or 420r). Although the illustrated embodiment includes four identically-dimensioned weights 420, 421, it will be understood for the purposes of these embodiments that there may be more or fewer weights having different dimensions depending on the particular application and desired performance of the buffer 240. The weights 420, 421 may also be made of different materials having different densities to arrive at the desired functionality for the particular application. Although the weights 420, 421 may be made of any ferrous or non-ferrous material, preferably the weights 420, 421 are made of a material that is as dense as, and that weighs an equal amount as or more than, stainless steel. In the illustrated embodiments, the weights 420 are preferably made of tungsten, or of another high-density metal material, and the weights 421 are preferably made of carbon steel, stainless steel, or some other material with similar properties. The weights 420 have planar, flat forward and rearward ends. The spacers 430 are positioned between the flat ends of adjacent weights 420, 421.
The illustrated embodiments also include a magnetic dead-blow biasing mechanism 460 in the form of a first magnet 450a and a second magnet 450b (the embodiment illustrated in FIG. 9 may or may not include a dead-blow biasing mechanism 460). In each embodiment, like poles (i.e., north or south) of the first and second magnets 450a, 450b face each other to create a repelling biasing force. Each embodiment has an at-rest condition which is the condition into which the internal assemblies 410, 510, 610, 710, 810, 910, 1010 (or more specifically the position into which the weights 420, 421) are biased by the magnetic dead-blow biasing mechanism 460. Each embodiment also has a dead-blow condition in which the biasing force of the dead-blow biasing mechanism 460 has been overcome by inertia forces that bring the magnets 450a, 450b into contact or into close proximity. The dead-blow biasing mechanism 460 resets the internal assemblies 410, 510, 610, 710, 810, 910, 1010 to the at-rest condition after a sufficient recovery time has passed following the occurrence of the dead-blow condition.
As will be explained below, the magnetic dead-blow biasing mechanism 460 can be configured to achieve the dead-blow condition at the end of the rearward stroke, the beginning of the rearward stroke, or at both the beginning and end of the rearward stroke. The magnetic dead-blow biasing mechanism 460 might be set up to achieve the dead-blow condition at the end of the rearward stroke when the action spring 230 is overly stiff or overly preloaded. In this situation, referred to as “oversprung,” the action spring 230 may cause the buffer 240 and bolt carrier 215 to transition from the rearward stroke to the forward stroke too quickly, which can cause the cycle of the action to operate too quickly. If the cycle of the action is too quick, the next round may not be properly gathered and loaded into battery condition by the bolt carrier 215. The magnetic dead-blow biasing mechanism 460 might be setup to achieve the dead-blow condition at the beginning of the rearward stroke when too much barrel gas is used to initiate the rearward stroke. In this situation, referred to as “overgassed,” the bolt carrier 215 jolts rearwardly too suddenly with the buffer 240, resulting in the bolt carrier 215 and the buffer 240 accelerating so quickly in the rearward direction that the bolt carrier 215 and the buffer 240 rebound off the rear end 220b of the buffer tube 220. The magnetic dead-blow biasing mechanism 460 may be set up to achieve the dead-blow condition at both the end and beginning of the rearward stroke when the action is slightly oversprung and overgassed.
One factor that must be considered when designing the magnetic dead-blow biasing mechanism 460 is a delay interval. The delay interval is the time it is expected to take for the weights 420, 421 to overcome the bias of the magnetic dead-blow biasing mechanism 460 and come to a dead-blow condition after an inertial event has occurred. Inertial events include the buffer 240 suddenly ceasing movement after being in motion and when the buffer 240 suddenly goes into motion from an at-rest position. Examples of inertial events arising from the buffer 240 suddenly ceasing movement include: (i) the buffer 240 striking the rear end 220b of the buffer tube 220 at the end of the rearward stroke; (ii) the buffer 240 striking the bolt carrier 215 during an initial period of the forward stroke if the buffer 240 and bolt carrier 215 become separated; and (iii) the bolt carrier 215 reaching the battery condition at the end of the forward stroke. Examples of inertial events arising from the buffer 240 suddenly going into motion include: (i) the start of the rearward stroke under the influence of barrel gases (by direct impingement or through a piston); and (ii) the start of the forward stroke under the influence of the action spring 230. The delay interval should be set to properly time the impact of the weights 420, 421 in the buffer 240 to offset a rebound 240 of the buffer 240 or to slow down an acceleration of the buffer 240.
An impact force provided by the weights 420, 421 after a delay interval reduces, minimizes, or eliminates bounce or rebound of the buffer 240 or slows down an acceleration of the buffer 240 after an inertial event. This effect is similar to the effect of a dead-blow hammer. For convenience, the dead-blow hammer effect just described is encompassed in the shorthand phrase “offset an inertial event.” To achieve the dead-blow hammer effect to offset an inertial event of the buffer 240 for desirable firearm 100 operation, the delay interval and the impact force must be fine-tuned. The proper combination of delay interval and impact force results in desirable operation of the firearm, and the delay interval and impact force that create this combination can be referred to as minimizing delay interval and minimizing impact force respectively. If these variables are not fine-tuned, the inertial event of the buffer 240 will not be offset.
For example, if the delay interval is too short, the weights 420, 421 will cause the impact force too soon after an inertial event. In this situation, the impact force does not create a dead-blow effect, but instead amplifies bounce or fails to slow down acceleration. Alternatively, if the delay interval is too long, the weights 420, 421 will cause the impact force too late after the inertial event. In this scenario, the impact force occurs after the buffer 240 has already bounced and the buffer 240 bounces for a second time during the same stroke. In addition, if the impact force provided by the front and rear weights is too small it will not sufficiently cancel out the bounce of the buffer. If the impact force of the weights is too great it will more than cancel out the bounce of the buffer and the excess impact force will cause bounce.
To fine tune the delay interval and impact force such that the inertial event is at least partially offset, the inertial event must be evaluated for relevant parameters. Relevant parameters include at least the acceleration of the buffer 240 and the bolt carrier 215, as well as the length of time over which the inertial event takes place. Using these parameters, the required minimizing delay interval and minimizing impact force for offsetting the inertial event can be determined. The properties of components of the firearm can then be adjusted so that the firearm assembly operates with the minimizing delay interval and the minimizing impact force required for desirable firearm operation.
The delay interval and the impact force are functions of multiple factors, including at least: the mass of the weights 420, 421; the travel distance between at-rest condition and dead-blow condition; friction; and strength (e.g., magnitude) of the magnetic force of the magnets 450a, 450b. The magnitude of the magnetic force of the magnets 450a, 450b is generally a function of: (i) the permeability of space between the first and second magnets 450a, 450b; (ii) the magnetic field strength of the first and second magnets 450a, 450b; (iii) a length of a face-to-face distance between the first and second magnets 450a, 450b; and (iv) geometry of the first and second magnets 450a, 450b.
In all the embodiments, the material of an encapsulation 440 may be changed, in the embodiment illustrated in FIGS. 4A and 4B, the material of the rear end cap 290 may be changed, in the embodiment illustrated in FIGS. 5A-8C, the material of the spacers 430 may be changed, and in the embodiment illustrated in FIG. 7, the material of the buffer body 270 may be changed to fine-tune permeability of space and thereby the magnetic force. A combination of changing these materials may be used as well. Other methods of altering the permeability of space between the first and second magnets 450a, 450b include introducing various gases into the buffer cavity 270c of the buffer body 270 to change the permeability of space of air in the buffer cavity 270c. Also, changing the thicknesses of any of the components between the first and second magnets 450a, 450b will alter the magnetic force, since the total permeability of space between the first is a weighted ratio of the permeability of space of all of the components within the space between the first and second magnets 450a, 450b. Altering the types of the first and second magnets 450a, 450b may also change the magnetic field strength of the first and second magnets 450a, 450b to alter the magnetic force, since magnetic field strength is an intrinsic material property.
The geometry of the first and second magnets 450a, 450b may also be changed to alter the magnetic force. Also, the face-to-face distance between the first and second magnets 450a, 450b at the rearward-inertia condition and the forward-inertia condition may be altered by changing the length of some or all of the weights 420, 421, the length of some or all of the spacers 430, the thickness of the encapsulation 440, and/or the distance that the rear end cap 290 extends into the buffer cavity 270c of the buffer 240. Altering the face-to-face distance adjusts both the initial starting magnetic force exerted between the first and second magnets 450a, 450b, as well as the way in which the magnetic force is exerted between the first and second magnets 450a, 450b over time. Altering any of the variables of which the magnetic force is a function, either alone or in combination, may change the magnitude of the magnetic force. By changing the magnitude of the magnetic force, the delay interval and the impact force are also changed, and may be adjusted to achieve the desired minimizing delay interval and minimizing impact force.
Turning now to the illustrated embodiments, FIGS. 4A and 4B illustrate an internal assembly 410 designed to specifically address an overgassed firearm 100. The illustrated internal assembly 410 includes a first magnet 450a disposed on a rear face of the rearmost weight 420r, and a second magnet 450b held entirely within (e.g., encapsulated in) the rear end cap 290. In some embodiments, a portion of the second magnet 450b may be exposed to the buffer cavity 270c rather than completely contained within the end cap 290. The magnets 450a, 450b are arranged such that their ends of a same polarity (north or south) face each other and the magnets 450a and 450b exert repellent magnetic forces on each other. Preferably, the encapsulation material 440 is injection molded nylon, copper or nickel plating, or hardened epoxy dip, but other materials with similar properties may be used. FIG. 4A illustrates the internal assembly 410 in the at-rest condition and FIG. 4B illustrates the internal assembly 410 in the dead-blow condition following an inertial event and the delay interval.
The internal assembly 410 operates as follows. The internal assembly 410 is in the at-rest condition (FIG. 4A) when the bolt carrier 215 is in the battery condition (i.e., full forward). The rearward stroke starts under the influence of barrel gases (by direct impingement or through a piston), which is an inertial event causing the buffer body 270 to jolt rearwardly. The impact force arising from this inertial event are absorbed by the resilient spacers 430. When the buffer 240 bottoms out in the buffer tube 220, another inertial event occurs and the weights 420, 421 slam into the rear end cap 290 (FIG. 4B) to achieve the dead-blow condition. The dead-blow condition offsets the inertial event to reduces bounce of the bolt carrier 215 and the buffer 240 off the rear end 220b of the buffer tube 220 and makes the buffer 240 pause before starting the forward stroke. The dead-blow biasing mechanism 460 resets the internal assembly 410 to the at-rest condition (FIG. 4A) while the buffer 240 pauses. Then the action spring 230 drives the buffer 240 forward into the battery condition. If the force of the action spring 230 is sufficiently quick and forceful another inertial event may occur to again achieve the dead-blow condition, followed by the dead-blow mechanism 460 resetting the internal assembly 410 to the at-rest condition. Otherwise the internal assembly 410 remains in the at-rest condition for the full forward stroke. The resilient spacers 430 absorb impact force at the end of the forward stroke when the buffer 240 achieves battery condition.
FIGS. 5A and 5B illustrate a second configuration of an internal assembly 610 of the buffer 240 designed to specifically address an oversprung firearm 100. The internal assembly 610 has all the same components as the first embodiment 410, and differs only in the configuration. In the internal assembly 610, the first magnet 450a is disposed on a front face of the forwardmost weight 420f, and the second magnet 450b disposed within the front end cap 280 such that a portion of the second magnet 450b is exposed to the buffer cavity 270c. In some embodiments, the second magnet 450b may be held entirely within (i.e., completely encapsulated) the front end cap 280. The forwardmost weight 420f and the second magnet 450b are encapsulated together within an encapsulation 440. FIG. 5A illustrates the internal assembly 610 in an at-rest condition and FIG. 5B illustrates the internal assembly 610 in the dead-blow condition following an inertial event and the delay interval.
The internal assembly 610 operates as follows. The internal assembly 610 is in the at-rest condition (FIG. 4A) when the bolt carrier 215 is in the battery condition (i.e., full forward). The rearward stroke starts under the influence of barrel gases (by direct impingement or through a piston). If the influence of the barrel gases is sufficiently quick and forceful an inertial event may occur to achieve the dead-blow condition, followed by the dead-blow mechanism 460 resetting the internal assembly 610 to the at-rest condition. Otherwise the internal assembly 610 remains in the at-rest condition for the full rearward stroke. The resilient spacers 430 absorb impact force at the end of the rearward stroke when the buffer 240 bottoms out in the buffer tube 220. The forward stroke then starts under the influence of the action spring 230, which is an inertial event causing the buffer body 270 to jolt forwardly. The impact force arising from this inertial event are absorbed by the resilient spacers 430. When the buffer 240 tops out into battery condition, another inertial event occurs and the weights 420, 421 slam into the front end cap 280 (FIG. 4B) to achieve the dead-blow condition. The dead-blow condition offsets the inertial event to reduce bounce of the buffer 240 off the rear end of the bolt carrier 215. The dead-blow biasing mechanism 460 resets the internal assembly 410 to the at-rest condition (FIG. 4A) before the next rearward stroke begins.
In the embodiments illustrated in FIGS. 4A-5B, during an inertial event at the end of a rearward stroke or a forward stroke, the internal assembly 410, 510 within the buffer 240 offsets an inertial event. At the end of a forward stroke (i.e., a forward-directed inertial event), the internal assembly 410, 510 prevents the buffer 240 from bouncing off of the bolt carrier 215. The bolt carrier 215 cannot bounce at the end of a forward stroke because the bolt carrier 215 is locked into the battery position. At the end of a rearward stroke (i.e., a rearward-directed inertial event), the internal assembly similarly prevents the buffer 240 from bouncing off of the rear end 220b of the buffer tube 220. However, the bolt carrier 215 may bounce off the buffer 240 at the end of a rearward stroke if the dead-blow mechanism is not properly tuned to the combined masses of the buffer 240 and bolt carrier 215, which is difficult to accomplish in a dynamic rapidly-moving system such as a firearm.
FIG. 6 illustrates a third configuration or embodiment of an internal assembly 710 of the buffer 240 which addresses both an oversprung firearm and bounce of the bolt carrier 215 off the buffer 240 at the end of a rearward stroke. The internal assembly 710 is most similar to the second embodiment 610 and operates in an similar manner. The embodiment illustrated in FIG. 6 differs from the embodiment illustrated in FIGS. 5A and 5B in that the first magnet 450b of the third embodiment disposed within the front cap 280 is thicker and therefore more powerful than the magnet 450b of the second embodiment. The thicker and more powerful magnet 450b of the third embodiment has an additional advantage in that a front face of the magnet 450b may exert a large enough magnetic attracting force on the bolt carrier 215 to bias the bolt carrier 215 and buffer body 240 towards each other (i.e., magnetically couple the bolt carrier 215 and buffer body 240 so that the two components effectively move together as a single component).
The bolt carrier 215 therefore remains biased towards the front end cap 280 of the buffer 240 over the entire course of a firing action of a firearm. When an inertial event occurs at the end of a rearward stroke, the bolt carrier 215 remains biased towards (magnetically coupled to) the buffer 240 such that any bounce not offset by the resiliency of the rear end cap 290 and resilient spacers 430 in the buffer 240 is overcome by the magnetic attraction to further reduce or eliminate bounce of the bolt carrier 215 off of the buffer 240 (i.e., physical separation of the bolt carrier 215 from contact with the buffer 240). Additionally, the bolt carrier 215 remains biased towards the buffer 240 during an inertial event at the end of a forward stroke. The magnetic attracting force acts together with the weights 420, 421 coming to a dead-blow condition to bias the buffer 240 towards the bolt carrier 215 to further offset the inertial event and further reduce the bounce of the buffer 240 off of the bolt carrier 215. In some embodiments, the magnetic attracting force between the bolt carrier 215 and buffer 240 may be sufficiently strong to maintain engagement between the bolt carrier 215 and the buffer 240 during the entire firing and reloading action of the firearm. Additionally, the strength of the magnetic dead-blow biasing mechanism 460 enables a resilient spacers 430 to be positioned in the space between the two magnets 450a, 450b to reduce noise.
FIG. 7 illustrates a fourth embodiment of an internal assembly 810 of the buffer 240. The internal assembly 810 is most similar to the third embodiment 710 and operates in an similar manner. The embodiment illustrated in FIG. 7 differs from the embodiment illustrated in FIG. 6 in that a portion of the magnet 450b is exposed to the internal space 225 of the upper receiver 110. The exposed portion of the magnet 450b has the additional advantage in that, the magnet 450b of the fourth embodiment exerts a stronger attractive magnetic force on the bolt carrier 215 than the magnet 450a of the third embodiment. By exerting a stronger force between the bolt carrier 215 and the front end cap 280, the bolt carrier 215 and the buffer 240 are more effectively hindered from bouncing away from each other, further increasing the accuracy of the firearm 100.
FIGS. 8A and 8B illustrate a fifth configuration of an internal assembly 910 of the buffer 240. The internal assembly 910 is most similar to the first embodiment 410. The dead-blow biasing mechanism 460 operates in an identical manner to that of the first embodiment 410 to address an overgassed firearm, but the embodiment illustrated in FIGS. 8A and 8B also includes a third magnet 450c. The third magnet 450c operates in a similar manner to second magnet 450b of the embodiments illustrated in FIGS. 6 and 7, to bias the bolt carrier 215 and the buffer 240 towards each other. The embodiment illustrated in FIGS. 8A and 8B has the added advantage that the third magnet 450c has a larger radius than the second magnet 450b of the embodiments illustrated in FIGS. 6 and 7. Specifically, the radius of the third magnet 450c is larger than a radius of the buffer cavity 270c. The front end cap 280 in this embodiment might be threaded onto the front end of the buffer body 270, with the third magnet 450c captured between the front end cap 280 and the front end of the buffer body 270. The third magnet 450c of the fifth embodiment is therefore more powerful than the second magnet 450b of the third and fourth embodiments, and exerts a stronger magnetic attracting force on the bolt carrier 215. This stronger magnetic attracting force further offsets the inertial event at the end of a rearward stroke or a forwards stroke, and thereby further prevents the bolt carrier 215 and the buffer 240 from bouncing off one another.
FIGS. 9A and 9B illustrate a sixth configuration of an internal assembly 1010 of the buffer 240. The internal assembly 1010 is most similar to the fifth embodiment 910, as the internal assembly 1010 includes a magnet 450c with a radius larger than the buffer cavity 270c. The magnet 450c operates in an identical manner to that of the embodiment illustrated in FIGS. 8A and 8B, to bias the bolt carrier 215 and the buffer 240 towards each other, and to thereby prevent the bolt carrier 215 and the buffer 240 from bouncing off one another. The internal assembly 1010 of the sixth embodiment illustrated in FIG. 9 however does not include a dead-blow biasing member 460 including a first magnet 450a and a second magnet 450b. In the embodiment illustrated in FIG. 9, the internal assembly does not include a dead-blow biasing member 460 at all. In other embodiments, the internal assembly 1010 may include a dead-blow biasing member 460 that is a spring or another dead-blow biasing mechanism known in the art.
The internal assembly 1010 operates as follows. The internal assembly 1010 is in an at-rest condition (FIG. 9A) when the bolt carrier 215 is in the battery condition. To begin a firing action, the rearward stroke occurs. If the rearward stroke is forceful enough, an inertial event may occur to achieve a dead-blow condition (FIG. 9B), followed by the spacers 430 absorbing impact force at the end of the rearward stroke when the buffer 240 bottoms out. Otherwise the internal assembly 1010 remains in the at-rest condition for the full rearward stroke until the buffer 240 bottoms out. When the buffer 240 bottoms out, another inertial event occurs and the weights 420, 421 slam into the rear end cap 290 to achieve a dead-blow condition (FIG. 9B). The dead-blow condition offsets the inertial event to reduce bounce of the buffer 240 off the buffer tube 220. Bounce of the bolt carrier 215 off of the buffer 240 at the end of a rearward stroke is also reduced by the magnet 450c, which exerts a magnetic attracting force on the bolt carrier 215 to bias the bolt carrier 215 towards the buffer 240. At the conclusion of the rearward stroke, the dead-blow condition of the rearward stroke (FIG. 9B) becomes the at-rest condition of the forward stroke. The forward stroke then starts, and if the forward stroke is forceful enough, an inertial event may occur to achieve the dead-blow condition of the forward stroke (FIG. 10B). The spacers 430 handle the impact force in this instance. Otherwise, the internal assembly remains in the at-rest condition for the full forward stroke until the buffer 240 tops out and creates another inertial event. The weights 420, 421 slam into the front end cap 280 to achieve the dead-blow condition, offsetting the inertial event and preventing bounce of the buffer 240 off of the bolt carrier 215. Bounce of the buffer 240 off of the bolt carrier 215 at the end of a forward stroke is also reduced by the magnet 450c, which exerts a magnetic attracting force on the buffer 240 to bias the buffer 240 towards the bolt carrier 215. At the conclusion of the forward stroke, the dead-blow condition of the forward stroke (FIG. 9A) becomes the at-rest condition of the rearward stroke as the next rearward stroke begins.
FIGS. 10A, 10B, and 10C illustrate a seventh embodiment of an internal assembly 510 of the buffer 240. The internal assembly 510 is similar to the first embodiment 410 but the first and second magnets 450a, 450b are disposed on adjacent faces of adjacent inner weights 420. An at-rest condition of the internal assembly 510 is illustrated in FIG. 10A and first and second dead-blow conditions of the internal assembly 510, following respective inertial events and delay intervals, are illustrated in FIGS. 10B and 10C.
Turning to FIG. 10B, at the end of the rearward stroke, an inertial event occurs which causes the front weights 420, 421f to overcome the magnetic biasing mechanism 460 and slide into contact with the rear weights 420, 421r with an impact force that is partially cushioned by the resilient spacers 430 to reduce noise and provide compliance. The impact force is of sufficient magnitude and of proper timing to reduce bounce of the buffer 240 and cause the buffer 240 to pause before starting the forward stroke. During the pause, the magnetic biasing mechanism 460 returns the internal assembly 510 to the at-rest condition illustrated in FIG. 10A.
With reference now to FIG. 10C, at the end of the forward stroke, an inertial event occurs which causes the rear weights 420, 421r to overcome the magnetic biasing mechanism 460 and slide into contact with the forward weights 420, 421f with an impact force that is partially cushioned by the resilient spacers 430 to reduce noise and provide compliance. The impact force is of sufficient magnitude and of proper timing to reduce bounce of the buffer 240 off the bolt carrier 215. Before the rearward stroke begins, the magnetic biasing mechanism 460 returns the internal assembly 510 to the at-rest condition illustrated in FIG. 10A.
Depending on the magnitude and acceleration of the beginning of the forward and rearward strokes, the biasing force of the magnetic biasing mechanism 460 can be overcome to move the weights 420, 421 into the first and second dead-blow conditions of FIGS. 10B and 10C, respectively.
Because only half of the plurality of weights 420, 421 in the embodiments of FIGS. 10A-10C are providing the impact force to reduce the bounce of the buffer 240 as compared to the embodiments of FIGS. 4A-9B, the impact forces provided in the embodiments of FIGS. 10A-10C are generally not as large as those provided by the embodiments of 4A-9. The properties of the weights 420, 421 (such as density, volume, etc.) can be altered so that the weights 420, 421 can provide the required impact forces for desirable operation of the firearm 100.
Thus, the invention provides, among other things, a buffer assembly that includes at least one magnet that offsets an inertial event that occurs during the firing action of a firearm. The magnet thereby reduces, minimizes, or eliminates bounce or rebound of the buffer at the rear end of the buffer tube and/or at the bolt carrier. Various features and advantages of the invention are set forth in the following claims.
Patent Application
20210025665
