Patent Application
20240302119
Not Applicable
Not Applicable
This invention relates to the field of firearms. More specifically, the invention comprises a magazine having a reduced collapsed spring height and consequently an increased internal capacity.
It is important to maximize space efficiency in detachable firearm magazines. This is particularly true for pistol magazines—where the magazine must fit inside the pistol's grip and therefore be encircled by the user's hand. Firearms manufacturers provide a fixed volume for the external dimensions of the magazine. The magazine must conform to this fixed volume in order to fit into the firearm. Thus, the external dimensions of a magazine intended for use in a particular firearm are essentially fixed.
The magazine's internal dimensions may vary somewhat, but these are constrained by the cartridge the magazine is designed to house. The magazine tube wall thickness and the cartridge diameter will largely fix the internal magazine width (width being perpendicular to the pistol bore) and internal length (length being parallel to the pistol bore). The internal height is also largely constrained since the top of the magazine tube (incorporating the cartridge feed lips and rails) must rest in a fixed position and the bottom of the magazine tube must also rest in a fixed position (often proximate the base of the pistol grip but sometimes below it for extended magazines). Thus, a magazine designer is constrained as to the internal dimensions as well.
A magazine is intended to (1) reliably feed the cartridges it houses while (2) containing a desired number of cartridges when fully loaded. As those skilled in the art will know, the cartridges within the magazine are forced upward by a magazine spring acting on a follower. The magazine spring is compressed between the base of the magazine tube and the follower. The follower bears against the cartridges and urges them upward toward the cartridge feed lips and rails.
The follower is urged downward—and the magazine spring is compressed—as more cartridges are loaded into the magazine. The number of cartridges that can be loaded is usually limited by the magazine spring reaching a fully compressed state and arresting the further downward motion of the follower. Significant effort has been directed to the design of followers and magazine springs in order to minimize the fully compressed height of the spring/follower assembly (thereby maximizing cartridge capacity). An example of this prior art work is described in U.S. Pat. No. 4,397,453 to Seecamp (1983). In the Seecamp design, successive coils in the magazine spring are nested so that multiple coils can collapse into the height of a single coil. This reduces the fully compressed height of the magazine spring.
An objective of the present invention is the provision of additional cartridge capacity in a magazine having standard external dimensions.
The present invention integrates a novel spring design with a novel interface between the top of the magazine spring and the follower to produce a reduced height when the magazine is fully loaded. The preferred embodiments of the magazine spring include a triple-nested bottom three coils, followed by an alternating succession of double-nested pairs of coils. The bottom three coils and the alternating pairs are configured to remain within a double stack portion of the magazine. The magazine spring also includes a transition portion-comprising elongated coils—configured to extend into the upper portion of the magazine when the magazine is nearly empty. The follower is preferably configured to receive the transition portion of the magazine spring into a lower spring receiver when the magazine spring is fully compressed. These features combine to provide a lower position for the follower when the magazine spring is fully compressed.
The following descriptions pertain to preferred embodiments of the present invention. Having reviewed these descriptions, many more embodiments will occur to those skilled in the art. Accordingly, the scope of the invention should be set by the claims presented at the end of this disclosure rather than the embodiments described.
The invention is well-suited to “double stack” magazines, in which at least a portion of the magazine houses two overlapping columns of cartridges.
Tube 12 provides the main structure of the magazine assembly. The term “tube” is conventional in the industry, even though the structure is not round. The tube is typically a thin-walled hollow structure, open at the top and bottom. Rearward wall 27 is generally perpendicular to the tube's side walls. Forward wall 25 is more rounded.
Base 14 can be any structure that is attached to the lower portion of the tube 12. It is preferable for the base to provide gripping features that facilitate the quick removal of the magazine. In the example of
Follower 16 slides up and down within the hollow interior of tube 12. The upper portion of the tube tapers inward. The very top portion of the tube preferably includes a pair of feed lips/rails (Some magazines incorporate a pair of rearward feed lips and a pair of forward feed rails. Pistol magazines, such as the one shown, often combine these features). The feed lips/rails properly locate a cartridge being fed by the magazine so that a moving slide will “strip” a fresh cartridge off the top of the magazine each time the firearm cycles. Follower 16 is sized so that it cannot escape through the feed lips/rails and out the top of the tube. The follower is thus captured within the tube. When the last cartridge is moved out of the magazine, follower 16 will be arrested in its fully raised position-which is shown in
The exemplary magazine assembly 10 has many other conventional features needed for the operation of a firearm. For example, magazine latch relief 20 receives a firearm magazine latch that holds the magazine in the firearm until a user releases the latch. Inward planar indentations 24 are provided in each of the side walls. These serve to guide the sides of the cartridges contained within the magazine and provide an additional volume rearward of the planar indentations for the rims of the cartridges. Angled indentations 26 (one on each side) assist the cartridges in traveling upward from the double-stack portion of the magazine and through a transition portion where the cartridges transition toward a single-stack configuration (though not necessarily a fully developed single-stack configuration).
Slide latch relief 22 is formed in the forward portion of follower 16. As those skilled in the art will know, a slide latch relief is needed so that—after the last round is fed from the magazine—a tab on the firearm's slide latch will move into relief 22 and cause the slide latch to hold the firearm's slide in the open position. Many other conventional features may be included in the inventive magazine. These include various types of feed lips, feed rails, and partial feed ramps. The inventive magazine may also include one or more openings that allow a user to see the number of cartridges contained in the magazine.
A magazine assembly is generally created by inserting the follower and spring through the open lower end of the tube. The spring is then compressed and the lower end of the tube is closed by the addition of a base. In this context the term “base” should be broadly understood to mean a component or assembly of components that restrains the lower end of the magazine spring. There are endless ways to attach a base to the magazine tube.
In
In order to remove the base from the tube, the user employs a pointed object to press upward on protrusion 38. This motion compresses spring 18 and raises protrusion 38 clear of opening 40. The user can then slide base 14 forward (to the left in the view of
Still looking at
The invention is not limited to a spring having any particular number of coils, but the example shown has 13 coils (with the first coil having an additional component and the thirteenth coil not being a complete coil). Each coil is given a number enclosed in a circle. A number enclosed in a circle therefore denotes a coil as a whole and not a particular portion of a coil.
Each coil has a first semi-circle of wire (the forward portion of the coil), a first straight portion, a second semi-circle (the rearward portion of the coil) and a second straight portion. Coil 1 has first semi-circle 54, first straight portion 56, second semi-circle 58, and second straight portion 60 (The reader will also note a “0th” straight portion that exists just prior to first semi-circle 54). Each successive coil going from bottom to top repeats this pattern. The circled label for each coil rests in the middle of the first semi-circle for that particular coil.
While the same nomenclature is used for the coils from bottom to top, the reader will note that the structure of the spring is by no means uniform. It is preferable to use a constant diameter spring wire for the entire spring, but the nature of the bends formed in the wire change and the shape of the coils differ. The differences allow some of the adjacent coils to nest together.
As those skilled in the art will know, the number of cartridges that can be loaded into a given magazine assembly is limited by the position of the follower when the spring is in a fully compressed state. An objective is to provide a lower position for the follower so that one or more additional cartridges can be loaded. Even a small difference in the follower's fully compressed position can be significant.
The spring wire in the example of
Before leaving
The alternating crossover pattern can be seen in comparison to parallel axes 64, 66. These two parallel axes are parallel to the side walls of the magazine tube. Straight portion axis 62 extends from the center of second straight portion 60 of Coil 6. The reader will note how second straight portion 60 of Coil 6 angles inward by an angle ∝2. Straight portion axis 64 extends from the center of second straight portion 60 of Coil 7. This second straight portion angles outward by an angle ∝1. The use of these angled portions allows the second straight portion of Coil 7 to pass over the top of the second straight portion of Coil 6. Similar crossovers are formed at other points—as can be seen in the view.
As stated previously, the design of the follower and the interaction between the follower and the spring provide another height savings when the spring is in a fully compressed state.
Chamfer 86 is provided on the upper rear portion of the follower. The chamfer is provided to ease the passing of a cartridge base over the top of the follower as the last round is fed into the firearm. The chamfer also allows the advancing breech face (on the slide) to pass over the top of the follower in the event the user releases the slide latch and returns the slide to its forward position after the last round is fired.
Left notch 74 and right notch 76 are provided on the lateral sides of the follower. Left notch 74 engages angled indentation 26 on the left side of the magazine. This interaction helps to center the follower as it travels upward toward the top of the tube. Right notch 76 engages the angled indentation on the right side of the magazine.
In
In other versions the follower may only house two or three coils in the fully compressed state. However, for the case of a 9 mm parabellum cartridge, housing four coils within the follower is desirable since this will lower the position of the follower's upper surface by four wire diameters—or about 0.200 inches. The reader will recall for the 9 mm parabellum cartridge that each additional 0.196 of internal magazine height allows the addition of one more cartridge in the double-stack configuration. Thus, the follower/spring interface shown allows the addition of one more cartridge.
The reader will thus understand that the inventive magazine assembly provides additional internal height (and thereby additional ammunition capacity in the same external form) by (1) optimizing the spring so that its fully compressed height is reduced, and (2) optimizing the follower/spring interface so that some upper spring coils are contained within the follower's spring receiver cavity when the spring is fully compressed-thereby allowing the follower to assume a lower position within the tube.
The same inventive enhancements can be added to a magazine having a taller tube. Using this approach a magazine ordinarily holding 17 rounds can be made to hold 19 rounds, while a magazine ordinarily holding 19 rounds can be made to hold 21 rounds.
Exemplary dimensions serve to aid the reader's understanding. Looking again at the specific example of
Looking at
The follower in the present invention preferably includes reliefs that allow the follower to move laterally with respect to the spring so that the follower can rest beside portions of the compressed spring. A follower can be configured to move to the left or the right. In the illustrated embodiments the follower moves to the left.
Central lateral relief 102 extends through both sides of the follower (the opposite side is visible in
The reason for this upward cant is found in the geometry of the cartridges themselves. The magazine depicted in the drawing views is configured to feed 9 mm Parabellum cartridges (also known as 9 mm Luger cartridges). As those skilled in the art will know, such cartridges have a tapered case. In such cartridges the rim diameter is typically 0.394 inches (10.01 mm). The case just forward of the rim has a diameter of 0.391 inches (9.931 mm). The diameter of the case neck is 0.380 inches (9.653 mm). When such cartridges are stacked in a magazine, they do not remain perfectly parallel. Instead, they naturally form a gradually curving arc because the rear portion of each cartridge is larger than the front portion.
The uppermost cartridge—the one about to be stripped from the magazine and loaded into the chamber—is preferably held parallel to the pistol's bore or possibly canted slightly upward. Each successively lower cartridge has an increased upward angle compared to the one just above. By the time the bottom of the magazine is reached, the upward cant is quite pronounced (as shown in
Still looking at
Many other variations will of course occur to those skilled in the art. The invention is not limited to any particular embodiment. The variations can be combined as well. A non-exhaustive listing of such variations includes:
Although the preceding descriptions contain significant detail, they should not be construed as limiting the scope of the invention but rather as providing illustrations of the preferred embodiments of the invention. Those skilled in the art will know that many other variations are possible without departing from the scope of the invention. Accordingly, the scope of the invention should properly be determined with respect to the following claims rather than the examples given.
