Patent ID: 12241711

REFERENCE NUMERALS IN THE DRAWINGS

10magazine assembly12tube14base16follower18spring20magazine latch relief22slide latch relief24planar indentation25forward wall26angled indentation27rearward wall28double stack portion30transition portion32feed relief34feed rail/lip36plate38protrusion40opening42cavity44lateral flange46lateral slot50rearward portion52forward portion54first semi-circle56first straight portion58second semi-circle60second straight portion62straight portion axis64straight portion axis66parallel axis68parallel axis70straight portion72straight portion74left notch76right notch78forward skirt80rearward skirt82curved cradle84ridge86chamfer88spring receiver cavity90forward boss92rearward boss94cartridge96forward guide surface98rearward guide surface100rear corner relief102central lateral relief104forward corner relief106right front leg108left front leg110right rear leg112left rear leg

DETAILED DESCRIPTION OF THE INVENTION

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.FIG.1provides a side elevation view of such a magazine assembly10. This disclosure uses a directional convention (upper, lower, forward, rearward, etc.) that is based on the firearm. The assumption is that the firearm's barrel is held in a horizontal position with a magazine well configured to receive the inventive magazine facing downward (so that the magazine is loaded into the well by moving it generally upward). “Forward” is toward the muzzle and “rearward” is the opposite. “Left” is the left side of the firearm and “right” is the opposite. “Width” refers to a measurement taken in a direction that is horizontal and perpendicular to the barrel. “Length” refers to a measurement taken in a direction that is parallel to the barrel. The orientation shown inFIG.1is the orientation in which a magazine will typically be used. The firearm into which the magazine is inserted—in this case a pistol—is normally held and fired upright with the magazine well being contained within a grip the user holds.

Tube12provides 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 wall27is generally perpendicular to the tube's side walls. Forward wall25is more rounded.

Base14can be any structure that is attached to the lower portion of the tube12. It is preferable for the base to provide gripping features that facilitate the quick removal of the magazine. In the example ofFIG.1, base14includes an expanding section that is easily grasped.

Follower16slides up and down within the hollow interior of tube12. 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. Follower16is 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, follower16will be arrested in its fully raised position-which is shown inFIG.1.

FIG.1includes a cutaway through the side wall facing the viewer. Spring18rests within the tube's interior—compressed between base14and follower16. The spring remains in a compressed state in all the normal operations of the magazine. The base is retained in a fixed position, so the degree of compression of the spring is determined by the vertical position of the follower within the tube. The spring urges the follower upward. The follower, in turn, urges the cartridges contained within the magazine upward.

The exemplary magazine assembly10has many other conventional features needed for the operation of a firearm. For example, magazine latch relief20receives a firearm magazine latch that holds the magazine in the firearm until a user releases the latch. Inward planar indentations24are 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 indentations26(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 relief22is formed in the forward portion of follower16. 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 relief22and 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.

FIG.2shows the same exemplary embodiment in a rear elevation view. The reader will note how the two side walls angle inward when traveling from double stack portion28of the magazine to transition portion30and ultimately to the vicinity of feed rails/lips34. The reader will note how the narrowing and partial closure of the top of the magazine tube “captures” follower16at the uppermost point in its travel. A cutaway in the rearward wall allows the reader to again see a portion of spring18.

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.FIGS.2-5illustrate one good approach.

InFIG.2, the reader will note a “callout” forFIG.5.FIG.5provides a detailed view of a portion ofFIG.2. InFIG.5, the reader will note how lateral flange44projects outward (to the left) at the bottom of tube12. A second lateral flange projects from the right side of the tube. Base14includes two lateral slots46designed to slidably engage the two lateral flanges44. The base attaches to the tube by sliding the two lateral slots46over the two lateral flanges44.

FIGS.3and4illustrate the selective removal of the base from the tube.FIG.3shows a sectional view through the middle of the assembly (note callout inFIG.2). Base14is secured to tube12via engagement of the lateral flanges on the tube with the lateral slots in the base. This arrangement allows the base to slide free of the tube when moved in the forward direction. However, the base is normally restrained by a second engagement. Plate36in this example is a thin metal plate that fits within the open bottom of the tube. Protrusion38extends downward form plate36. Base14includes an opening40positioned to receive protrusion38as shown. Cavity42is preferably provided in the lower portion of base14to provide access to opening40.

In order to remove the base from the tube, the user employs a pointed object to press upward on protrusion38. This motion compresses spring18and raises protrusion38clear of opening40. The user can then slide base14forward (to the left in the view ofFIG.3) to remove the base from the tube.FIG.4shows base14after it has been moved free of tube12. The reader will note that lateral slots46in the base are clear of the lateral flanges on the tube. At this point plate36is free to slide out the bottom of the tube, along with the magazine spring and follower.

Still looking atFIG.4, the reader will note how plate36in this embodiment has an upward tilting rearward portion50and an upward tilting forward portion52. These tend to center the first coil of the magazine spring on plate36. Many other variations are possible for the base. In some of these embodiments a depression can be integrally molded into the upward-facing surface of the base and this helps to locate the lower portion of the magazine spring. The invention is not limited to any particular type of base or combination of base and plate.

FIGS.6and7provide two perspective views of the spring in an uncompressed state. As those skilled in the art will know, the magazine is always in a compressed state when installed in the tube. However, it is helpful to illustrate the structure of the spring in an uncompressed state so that the individual coils are easier to see.FIG.6is a perspective view from a vantage point off to the left, forward side of the spring.FIG.7is a perspective view from a vantage point that is to the rear of the spring.

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-circle54, first straight portion56, second semi-circle58, and second straight portion60(The reader will also note a “0th” straight portion that exists just prior to first semi-circle54). 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.

FIG.7serves well to illustrate the differences in the coils. Adjacent coils nest within straight portion70. However, the nesting scheme is not uniform in this embodiment. The first three coils (Coils 1, 2 and 3) are configured to nest together to a fully compressed height of one spring diameter. The next two coils (Coils 4 and 5) are configured to nest together to a fully compressed height of one spring diameter. The next two coils (6 and 7) are configured to nest together to a fully compressed height of one spring diameter. Coils 8-13 stack without nesting. This adds an additional 5 wire diameters to the fully compressed height of the spring. Without nesting the overall fully compressed height of the spring would be 13 wire diameters. With the nesting configuration illustrated, the fully compressed height is approximately 9 wire diameters.

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 ofFIGS.6and7has a diameter of 0.050 inches (1.27 mm). Reducing the compressed spring height by 4 wire diameters produces a total height reduction of 0.200 inches (5.08 mm). The significance of this reduction may be seen by considering the base diameter of a common cartridge—the 9 mm parabellum. This cartridge has a base diameter of 0.392 inches (9.96 mm). In a single-stack magazine a designer must “find” an additional 0.392 inches of internal height to add another cartridge to the magazine's fully loaded state. However, in a double-stacked configuration, each additional cartridge only requires an additional height of ½ the base diameter (0.196 for a 9 mm parabellum cartridge). Thus, the improvement to the spring overall compressed height admits at least one additional cartridge. Improvements to the spring/follower interface provide an additional height savings which allow for at least one more additional cartridge—as will be described subsequently.

Before leavingFIG.7, another point to be noted is the alternating crossover pattern of the second straight portions60in Coils 3 through 8. A conventional spring collapses into a helical “stack” with the helix angle being present. The alternating crossover pattern for the second straight portions60of the inventive spring allows the spring to collapse into a more fully flattened state. In addition, the collapsing pattern created does not induce significant rotation of the ends of the spring.

The alternating crossover pattern can be seen in comparison to parallel axes64,66. These two parallel axes are parallel to the side walls of the magazine tube. Straight portion axis62extends from the center of second straight portion60of Coil 6. The reader will note how second straight portion60of Coil 6 angles inward by an angle ∝2. Straight portion axis64extends from the center of second straight portion60of 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.FIG.8provides a perspective view of a follower16. Forward skirt78descends from the forward portion of the follower and rearward skirt80descends from the rearward portion. The upward-facing surface includes curved cradle82. Ridge84blends curved cradle82into the upper portion of the follower. The curved cradle is shaped to engage the cylindrical exterior surface of the lowermost cartridge in a stack of cartridges. The shape of the cradle urges that cartridge to the right and upwards.

Chamfer86is 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 notch74and right notch76are provided on the lateral sides of the follower. Left notch74engages angled indentation26on the left side of the magazine. This interaction helps to center the follower as it travels upward toward the top of the tube. Right notch76engages the angled indentation on the right side of the magazine.

FIG.9shows the downward-facing portion of the follower. The lower portion opens into a hollow spring receiver cavity88. The cavity is located between forward skirt78and rearward skirt80(and extends upward into the interior of the follower). Spring engagement features are preferably included. In this example, forward boss90and rearward boss92extend downward within the spring receiver cavity in order to engage the top of the spring.

FIG.10provides an exploded perspective view of follower16and the top of the spring. Second semi-circle58of Coil 12 fits around rearward boss92. First semi-circle54of Coil 13 fits around forward boss90. These features positively connect the follower to the spring.

FIG.13provides a sectional view through the mid-plane of follower16with spring18installed. The forward part of the follower includes forward guide surface96—which is positioned to smoothly slide along the interior of the forward portion of the tube. The rearward part of the follower includes rearward guide surface98—which is positioned to smoothly slide along the interior of the rearward portion of the tube. These two guide surfaces act to maintain the follower in the desired orientation (parallel to the cartridges and the feed rails) without allowing it to pitch and thereby interrupt the desired travel.

InFIG.13the reader will also note how spring receiver cavity88is able to encompass the top four coils (Coils 10-13) of the magazine spring when the spring is in a fully compressed state. Note that Coil 9 is shown only partially compressed, but this is just to allow the reader to easily visualize how the top four coils can be contained within the follower.

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.

FIGS.11and12serve to illustrate the significant advantage of the present invention. The outside dimensions of the magazine assembly12shown inFIG.11ordinarily permit a magazine capacity of 15 cartridges. With the internal height advantages of the present invention, the same magazine is able to house 17 cartridges.

FIG.11shows a rear elevation view of magazine assembly10. A rear cutaway is provided so that the internal features can be seen. At this time 5 cartridges (labeled 1-5) are loaded in the magazine. Follower16lies in an intermediate position within the tube. Curved cradle82engages the lowermost cartridge and ridge84ensures that the lowermost cartridge is urged to the right. The follower is shown centered within the space to show the interaction between the curved cradle82and the lowermost cartridge. This relationship is in fact what would exist with the follower advance up toward the top of the tube. In the state shown, follower16will likely be positioned more to the left (as spring18deflects to the left). It will still urge cartridge 5 upward and against the right wall of the magazine, however.

FIG.12shows the same magazine when it is loaded to its maximum capacity. The straight portion70and transition portion72of the spring have been fully compressed. The straight portion is fully nested-meaning that all the nesting arrangements of the adjacent springs have been achieved. The transition portion for the spring does not nest. However, the reader will note how most of the transition portion (typically four coils) is contained within the spring receiver cavity of follower16. In this state it is possible to load 17 cartridges in a magazine that would ordinarily only hold 15.

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 ofFIG.7, the maximum width for each coil is presented (in inches/mm) in the following table:

COILWIDTH10.814/20.720.690/17.530.580/14.740.690/17.550.580/14.760.690/17.570.580/14.780.690/17.590.540/13.7100.342/8.69110.330/8.38120.330/8.38130.330/8.38

Looking atFIG.6, the nesting scheme for straight portion70(the first 8 coils) is very complex to describe. A table will be presented to describe the nesting characteristics. A system of simplified nomenclature is needed. As explained previously, each coil has a first semi-circle54, a first straight portion56, a second semi-circle58, and a second straight portion60. Each of these four portions of a coil will be abbreviated as “1SC,” “1SP,” “2SC,” and “2SP” (respectively). In the system of nomenclature, the coil to which a particular portion belongs will be provided after a “/.” Thus, the characters “1SC/1” shall refer to the first semi-circle of Coil 1. As an additional example, “2SP/C2” refers to the second straight portion of Coil 2. The term “inside” means one component nests toward the interior of the coil with respect to another component. The term “outside” means one component nests toward the exterior of the coil with respect to another component. The term “over” means that one component passes above another component (It crosses over the top). With this convention in mind, the nesting scheme of the embodiment ofFIG.7is described by the following table:

Coil1SC1SP2SC2SP1————2inside 1SC/C1inside 1SP/C1inside 2SC/C1inside 2SP/C13inside 1SC/C2inside 1SP/C2inside 2SC/C2over 2SP/C24outside 1SC/C3outside 1SP/C3outside 2SC/C3over 2SP/C35inside 1SC/C4inside 1SP/C4inside 2SC/C4over 2SP/C46outside 1SC/C5outside 1SP/C5outside 2SC/C5over 2SP/C57inside 1SC/C6inside 1SP/C6inside 2SC/C6over 2SP/C68outside 1SC/C7over 1SP/C7over 2SC/C7over 2SP/C79over 1SC/C8over 1SP/C8over 2SC/C8over 2SP/C810over 1SC/C9over 1SP/C9over 2SC/C9over 2SP/C911over 1SC/C10over 1SP/C10over 2SC/C10over 2SP/C1012over 1SC/C11over 1SP/C11over 2SC/C11over 2SP/C1113over 1SC/C12over 1SP/C12——

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.FIG.14shows a view of the right rear side of follower16. The follower shown is the same embodiment as depicted in the other figures.

Central lateral relief102extends through both sides of the follower (the opposite side is visible inFIG.8). Forward skirt78lies forward of central lateral relief102and rearward skirt80lies to the rear of central lateral relief102. The reader will note, however, that the right side of both skirts include additional reliefs. Rear corner relief100is provided on the right side of rearward skirt80. Forward corner relief104is provided on the right front of forward skirt78.

FIG.9shows the follower from underneath. The presence of rear corner relief100means that right rear leg110(the lowest portion of the right rear) is higher than left rear leg112. Left front leg108provides a nearly constant elevation while right front leg106is relieved by the curved forward corner relief104. The net result is that a portion of the spring can extend laterally out the right side of the follower and the follower can therefore translate to the left as the spring is compressed.

FIG.15is provided to better illustrate the advantage of the features allowing the lateral movement of the follower with respect to the spring.FIG.15shows a detailed elevation view of follower16and spring18when the spring approaches the fully compressed state. The reader will note inFIG.15that follower16is actually canted upward in comparison to its orientation inFIG.2. The upward cant can be easily seen via the fact that curved cradle82slopes upward (It rises when proceeding in a direction away from the viewer). The cartridges are shown only as phantom lines, but the reader will note that the cartridges proximate the bottom of the magazine are also canted upward.

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 inFIG.15). Left rear leg112is at or very near the same elevation as left front leg108. Right rear leg110is higher because of the inclusion of rear corner relief100(seeFIG.14).

Still looking atFIG.15, the reader will note how follower16has moved to the left with respect to spring18. The inclusion of reliefs100,102, and104allows an upper portion of the spring to extend out the right side of the follower-thereby allowing the follower to move to the left and sit beside a portion of the compressed spring18. This feature allows the follower to sit in a lower position when the spring is fully compressed.

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:1. A coil nesting scheme in which four or more adjacent coils are nested.2. A follower made of molded polymer.3. A follower made of metal.4. A magazine assembly with a metal tube.5. A magazine assembly with a molded polymer tube.

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.