Patent Application
20140096671
The present invention relates to firearms, and more particularly to a drum magazine for rimmed ammunition.
A drum magazine is a type of firearms magazine that is cylindrical in shape, similar to a drum. Instead of rounds being stored flat, as in a more common box magazine, rounds in a drum magazine are stored in a circle around the center of the magazine, facing the direction of the barrel. Drum magazines for rimmed ammunition, including shotgun shells, primarily run off a cogged (gear-shaped) design which feeds each individual round of ammunition from the outermost edge of the shell. Recently, a single stack compact design has been developed that uses most of the interior capacity of the drum. It is driven by a single hub and a telescopic shaft.
The advantage over traditional box-shaped magazines is that a drum magazine can carry much more ammunition, often two to three times that of a box magazine, without making it too big to be impractical to carry. The downside to drum magazines is that they increase the overall weight of the weapon in which they are being used, and they are more prone to jamming because of rim lock when used with rimmed ammunition. Shotgun shells have a wide variation in tolerances for overall length, so they are processed and positioned based on contacting their rims.
Rim lock is caused by the rims of improperly stacked shotgun shells impeding each other from feeding into the firearm. Rim lock occurs when the rim of the uppermost shell is positioned behind the rim of the shell immediately below. As a result, the uppermost shell cannot feed forward into the firearm, resulting in a jammed magazine.
Therefore, a need exists for a new and improved drum magazine that prevents rim lock of rimmed ammunition, especially shotgun shells. in this regard, the various embodiments of the present invention substantially fulfill at least some of these needs. In this respect, the drum magazine according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of providing the additional capacity of a drum magazine while preventing the rimmed ammunition from jamming.
The present invention provides an improved drum magazine, and overcomes the above-mentioned disadvantages and drawbacks of the prior art. As such, the general purpose of the present invention, which will be described subsequently in greater detail, is to provide an improved drum magazine that has all the advantages of the prior art mentioned above.
To attain this, the preferred embodiment of the present invention essentially comprises a body defining an interior and having a rear wall, a rotor rotatably mourned within the interior of the body, the rotor having a periphery defining a plurality of cartridge-receiving spaces, the rotor positioned to define a rim path proximate the rear wall, such that rims of cartridges received by the rotor periphery are proximate the rear wall, and a first rim-engagement element within the interior of the body and proximate the rim path, such that the rims of cartridges passing by the first element are contacted to axially shift each cartridge with respect to a subsequent cartridge. The first rim-engagement element may be a raised protrusion on the body. The rims of cartridges passing by the first rim-engagement element may be contacted to actually shift each cartridge rearward with respect to a subsequent cartridge. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims attached.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated.
The same reference numerals refer to the same parts throughout the various figures.
An embodiment of the drum magazine of the present invention is shown and generally designated by the reference numeral 10.
The drum housing 12 is a hollow cylindrical body having a closed front 14, an open rear 16, a perimeter 18, and an interior 64 (shown in
The tower 22 also has a front 24, a rear 26, a top 28, and a hollow interior 86 (shown in
The rear cover 48 has a front 100, rear 102, and an interim 98 (shown in
The rotor 60 has a front sprocket 72 and a rear sprocket 66 that are connected to the hub 76 by spokes 62. The front sprocket has teeth 74 that define cartridge-receiving spaces in the form of recesses 76. The rear sprocket has teeth 68 that define cartridge-receiving spaces in the form of recesses 70. The recesses are paired to receive the fronts 40 and rears 82 of the shotgun shells 38. The front sprocket is slightly offset clockwise with respect to the rear sprocket so that the front of each shell is positioned to the right of the rear of each shell. The rear of each shell forms a rim 84. The center to center spacing of the recesses is greater than the diameter of the rims of the shells. In the current embodiment, the sprockets, spokes, and hub are manufactured as a single integral part.
As the rotor 60 rotates in a clockwise direction, the shotgun shells are directed upwards into the interior 86 of the tower 22 by the guide plate 84. Rotation of the rotor is limited by a radially protruding stop 88 when the stop encounters a guide plate 84 that is attached to the interior of the drum housing below the opening 106. This state occurs when the drum magazine 10 has been emptied and needs to be reloaded.
Referring now to
The rim lock prevention features of the drum magazine 10 enact their forces and force alignment to prevent rim lock just before, and at the time of each shell's transition, from the divided sprocket cogs 70, 76 to direct shell-to-shell contact and tension. The manipulation of the shells 92, 94 is only possible before the transition to tension, which occurs the moment the shells leave the support of the drum sprocket cogs and are forced upon each other. After this occurs, further manipulation of the shell rims is impossible.
In the context of the specification, the terms “rear” and “rearward,” and “front” and “forward” have the following definitions: “rear” or “rearward” means in the direction away from the muzzle of the firearm while “front” or “forward” means it is in the direction towards the muzzle of the firearm.
While a current embodiment of a drum magazine has been described in detail, it should be apparent that modifications and variations thereto are possible, all of which fall within the true spirit and scope of the invention. With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.
Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
