Patent Application
20140165444
The present invention relates to firearms, and more particularly to firearms with changeable barrels.
Firearms with changeable barrels are desirable because the barrel can be replaced as the barrel becomes damaged or too hot, to change the firearm's caliber, or for more compact storage of the firearm.
Heavy machine guns, particularly those with air cooled barrels, often require barrel changes in the field because the barrel has become too hot for continued use without permanently damaging the barrel. Various quick-change mechanisms using latches or pins have been developed to permit rapid barrel replacement of heavy machine guns.
Although a variety of bolt action and semi-automatic and automatic rifles permit barrel changes, they typically require specialized tools. For example, to change an AR-15 barrel, the upper receiver is held in a vise block to provide a secure and steady hold on the upper receiver, a specialized barrel nut wrench is used to unscrew the barrel nut so the barrel can be removed, and a torque wrench must be attached to the specialized barrel nut wrench in order to tighten the barrel nut once the new barrel is in place. An alternative modular rifle system design eliminates the need for a vise block, but requires attaching a specialized takedown/assembly tool to the receiver and using a gear drive torque wrench to engage gear teeth on a specialized barrel design in order to tighten and loosen the barrel.
The disadvantages of both of these approaches are the need for specialized tools and associated difficulties associated with changing barrels in the field. Not only is there a risk of under torqueing or over torqueing the receiver or barrel nut, resulting in loosening or breakage, but it is also easy to lose the aim of an attached scope. The user may not notice the misalignment of the scope until after taking a shot that misses or strikes an unintended target.
Therefore, a need exists for a new and improved firearm that can be used to change barrels having a standard barrel thread in such a manner that under torqueing or over torqueing are not possible and an attached scope is unlikely to be disturbed. In this regard, the various embodiments of the present invention substantially fulfill at least some of these needs. In this respect, the firearm with barrel cinching clamp 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 facilitating barrel replacement when the barrel becomes damaged or too hot, to change the firearm's caliber, or for more compact storage of the firearm.
The present invention provides an improved firearm with barrel cinching clamp, 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 firearm with barrel cinching clamp that has all the advantages of the prior art mentioned above.
To attain this, the preferred embodiment of the present invention essentially comprises a receiver having a forward portion defining an internally threaded bore, a barrel having a threaded end removably received in the bore, at least a selected portion of the forward portion being split by a gap, the selected portion having connection elements on opposite sides of the gap, and an adjustable element connected to the connection elements and operable to narrow the gap to secure the barrel in the bore and to widen the gap to permit the barrel to be readily unscrewed from the bore. The bore may define a bore axis, and the gap may be parallel to the bore axis. A circumferentially complete portion of the threaded bore including a plurality of threads adjacent to the gap may be unbroken by a gap. The circumferentially complete portion of the threaded bore may be forward and/or rearward of the selected portion. 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.
A preferred embodiment of the firearm with barrel cinching clamp of the present invention is shown and generally designated by the reference numeral 10.
The front 38 of the receiver defines a threaded bore 50. The rear 80 of the barrel has barrel threads up until the point where a flange 84 circumferentially protrudes from the barrel. The barrel threads engage the threaded bore to secure the barrel in place. A clearance space 76 exists between the bore threads 86 and the flange to facilitate the mating of the barrel threads with the bore threads. A clearance space also exists between the top 78 of the chassis 14 and the right boss 52 and left boss 54 (only the left boss 54 is visible) that extend downwards from the bottom 40 of the receiver so the bosses are free to move. The bosses will be described in more detail subsequently.
Tightening the hex bolt head 62 creates a clamping action between the hex bolt head 62 and the threaded portion 64 engaged with the threaded bore 58 in the left boss 54. The clamping action draws the right boss 52 and left boss 54 together, thereby securing the barrel 16 in position within the threaded bore 50 in the front 38 of the receiver 12 by narrowing the central gap 44. A clearance space 78 between the right and left bosses and the chassis 14 permits the bosses to be drawn together. A belleville washer 88 is located below the hex bolt head to give a flexible quality to the bolted joint.
To remove the barrel 16 from the receiver, the hex bolt 60 is loosened by rotating the hex bolt head 62 counterclockwise. With the clamping pressure released, the right boss 52 and left boss 54 spring back to their uncinched positions and return the central gap 44 to its original width. In this position, the right boss and left boss permit the barrel to be readily unscrewed from the threaded bore 50 in the front 38 of the receiver 12. Subsequently, the barrel can be pulled forward for withdrawal and replaced with a new barrel of the desired caliber. The hex bolt is then replaced and tightened to secure the new barrel in position.
The hex bolt 60 of the current invention can be tightened and loosened by a conventional Allen wrench rather than a specialized tool. In addition, an appropriately sized Allen wrench may be securely received in the buttstock of the firearm 10 to make the wrench readily available to the user in the field.
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 in the direction towards the muzzle of the firearm.
While a current embodiment of the firearm with barrel cinching clamp 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.
