Multi-Caliber Bolt Assembly and Method of Using Different Sizes of Ammunition in a Firearm

This application claims the benefit of pending U.S. Provisional Patent Application No. 63/644,690, filed May 9, 2024, which is incorporated by reference herein.

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The disclosure relates to bolts for firearms and more particularly pertains to a new multi-caliber bolt assembly that includes a case guide and an extractor designed to allow the user to chamber a variety of ammunition types of various sizes and configurations in the same firearm without the need to change the bolt. Firearm bolts are designed to guide the rear of ammunition cases, wherein each firearm bolt has an extractor designed to handle an ammunition case of a specific size and caliber, and thus a firearm bolt will not allow for different types and calibers to be used in a single firearm. The new multi-caliber bolt assembly is designed to automatically adjust for various ammunition dimensions. Throughout the loading, firing, and ejection cycles of a firearm, the case guide, the extractor, and the bolt face work together to keep the ammunition under control at all times.

The prior art relates to bolts for firearms. The prior art, as best understood, does not disclose a multi-caliber bolt assembly includes a bolt body, a bolt face, an extractor, a case guide, and a resilient element, wherein the resilient element is designed to exert a force to move the extractor and the case guide together to engage and hold the cartridge casing against the bolt face when the extractor and the case guide are moved apart against the force by insertion of the cartridge casing between the extractor and the case guide regardless of the size of the cartridge casing.

An embodiment of the disclosure meets the needs presented above in a multi-caliber bolt assembly generally comprising a bolt body, a bolt face, an extractor, a case guide, and a resilient element. The bolt face is positioned at an end of the bolt body. The bolt face is designed to engage a cartridge casing for chambering. The extractor is movably coupled to the bolt body. The extractor is designed to engage and retain a rim of the cartridge casing. The case guide is movably coupled to the bolt body opposite the extractor. The case guide is designed to engage the cartridge casing together with the extractor. The resilient element is coupled to the extractor and the case guide. The resilient element is designed to exert a force to move the extractor and the case guide together to engage and hold the cartridge casing against the bolt face when the extractor and the case guide are moved apart against the force by insertion of the cartridge casing between the extractor and the case guide regardless of the size of the cartridge casing.

There has thus been outlined, rather broadly, the more important features of the disclosure 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. There are additional features of the disclosure that will be described hereinafter and which will form the subject matter of the claims appended hereto.

The objects of the disclosure, along with the various features of novelty which characterize the disclosure, are pointed out with particularity in the claims annexed to and forming a part of this disclosure.

With reference now to the drawings, and in particular tothereof, a new multi-caliber bolt assembly embodying the principles and concepts of an embodiment of the disclosure and generally designated by the reference numeralwill be described.

As best illustrated in, the multi-caliber bolt assemblygenerally comprises a bolt body, a bolt face, an extractor, a case guide, and a resilient element. The bolt faceis positioned at an end of the bolt body. The bolt faceis designed to engage a cartridge casingfor chambering. The extractoris movably coupled to the bolt body. The extractoris designed to engage and retain a rimof the cartridge casing. The case guideis movably coupled to the bolt bodyopposite the extractor. The case guideis designed to engage the cartridge casingtogether with the extractor.

As best seen in, the resilient elementis coupled to the extractorand the case guide. The resilient elementis designed to exert a force to move the extractorand the case guidetogether to engage and hold the cartridge casingagainst the bolt facewhen the extractorand the case guideare moved apart against the force by insertion of the cartridge casingbetween the extractorand the case guideregardless of the size of the cartridge casing. The extractorand the case guidework together to maintain the ammunition centered and aligned with a chamber or a barrel throughout the loading and firing cycle, which can happen at a very high rate of speed, such as 18 cycles per second. The extractorand the case guidework together to control the movement of the ammunition throughout the loading and firing cycle to prevent the ammunition from jamming or becoming misaligned or dislodged.

In the exemplary embodiment in, the extractorincludes a first extractor end, a second extractor end, and a pivot pinpositioned between the first extractor endand the second extractor endto pivotably mount the extractoron the bolt body. The case guideincludes a first case guide end, a second case guide end, and a pivot pinpositioned between the first case guide endand the second case guide endto pivotably mount the case guideon the bolt body. The resilient elementis coupled to and between the second extractor endand the second case guide end.

The resilient elementis designed to compress when the first extractor endand the first case guide endare moved apart by the cartridge casingand the second extractor endand the second case guide endare thereby moved toward one another. The resilient elementis designed to resiliently expand to exert the force to move the second extractor endand the second case guide endapart to thereby move the first extractor endand the first case guide endtoward one another to engage and hold the cartridge casingthroughout the feeding, loading, and firing process.

In this exemplary embodiment, the resilient elementis a spring. The springis a coil spring, though leaf springs or other types of springs could be used. However, in another possible embodiment, different resilient structures, such as elastomeric, elastic, or rubber elements, could be used. The resilient elementcould also be positioned elsewhere, such as coupled to the first extractor endand the first case guide end.

The first extractor endincludes a hookdesigned to be inserted into a case rim groovein the cartridge casingbehind the rimof the cartridge casingto engage a front rim faceof the rimto pull the cartridge casingout of a chamber of a firearmafter firing. As best seen in, the first case guide endincludes an outward protrusiondesigned to engage an outer rim edge of the rimof the cartridge casingto press the cartridge casingagainst the first extractor end. The outward protrusionis an outward protrusion that is generally rounded or bulging or convex or substantially convex and not pointed like the hook. Also unlike the hook, the outward protrusiondoes not project into the case rim groove, such that the outward protrusionengages to grip or hold the cartridge casing, but does not retain the cartridge casingagainst axial forward movement like the hookdoes.

The hookand the outward protrusionare designed such that, during ejection of the cartridge casingfrom the firearm, the outer rim edge is pushed out of engagement with the outward protrusionand the cartridge casingis pivoted around the hookin engagement with the rear face of the rimand out of the firearm. This action can be done manually by loading a round by hand, such as with a bolt action rifle, or automatically during reloading after firing from a cartridge, such as with an automatic or semi-automatic firearm.

In the exemplary embodiment in, each of the hookand the outward protrusionincludes curved or beveled side surfaces for insertion of the cartridge casingin an upward direction perpendicular to a longitudinal axis of the cartridge casing.

The bolt bodyincludes a pair of recessed slotsopening in the bolt face. Each of the case guideand the extractoris positioned in a respective one of the recessed slots. In the exemplary embodiment in, each of the case guideand the extractoris designed to engage and be stopped by a slot surfaceof a respective one of the recessed slotswhen pivoted maximally toward one another.

The multi-caliber bolt assemblyallows a user to use different sizes of ammunition, such as different calibers of ammunition, in a firearm. Further, the multi-caliber bolt assemblymaintains control of the ammunition and the cartridge casingduring all phases of operation. The bolt bodyis designed to reciprocate within a receiveror slide of a firearm. Generally speaking, the user loads a first cartridge casingof a first diameter in between the extractorand the case guideand thereby spaces the extractorand the case guideapart a first distance corresponding to the first diameter. The user then ejects the first cartridge casing, usually after firing the firearm. The user can then load a second cartridge casingof a second diameter different than the first diameter in between the extractorand the case guideand thereby space the extractorand the case guideapart a second distance corresponding to the second diameter. The second distance is different than the first distance.

show an example of this concept. In, the first cartridge casingis a smaller caliber having the first diameter, whereas in, the second cartridge casingis a larger caliber having the second diameter, which in this scenario is larger than the first diameter, though these could be reversed. Because of the springand the pivoting design of the extractorand case guide, the extractorand case guidecan be moved further apart in order to accommodate the second cartridge casingbut will be automatically moved closer together when engaging the first cartridge casing, and vice versa. Therefore, regardless of the size and/or caliber of the ammunition, the multi-caliber bolt assemblycan handle the ammunition, unlike standard bolt devices that only are designed to handle one type or size or caliber of ammunition.

To further explain, the figures show in detail the operation of the multi-caliber bolt assembly.shows the multi-caliber bolt assemblyinstalled in a firearm. The multi-caliber bolt assemblyfunctions like most any known bolt in the firearm. As shown in, the multi-caliber bolt assemblyholds the cartridge casingaligned with a barrel of the firearm.

show how the multi-caliber bolt assemblyengages and moves the cartridge casingforward into the barrel. This operation is further shown in. InA, the extractorand the case guideare positioned above the cartridge casing. In the exemplary embodiment, the ammunition is located in a magazine and is ready to be advanced upward and forward along a ramp, such as a ramp, into the barrel. However, in other possible embodiments, the magazine could be replaced with various types of ammunition feeding devices, such as tubes, as are well known in the firearms industry.

As shown in, as the ammunition is moved forward by the bolt body, the ammunition deflects on the ramp, which in turn pushes the cartridge casingup between the extractorand the case guide, which are consequently forced apart against the force of the spring. As shown in, and the ammunition is moved even further forward and upward along the ramp, the cartridge casingis now centered in between the extractorand the case guide.

show another feature in the operation of the multi-caliber bolt assembly. As mentioned above, the extractorhas a hookthat projects into the case rim grooveof the cartridge casing. Once the ammunition has been fired and it is time to eject the cartridge casing, the multi-caliber bolt assemblyretracts and the cartridge casingis engaged by an ejector (not shown) as is standard in firearms. Since the case guideis only pressing against the rim, the cartridge casingis pushed past and out of engagement with the case guide. However, since the hookof the extractoris engaged in the case rim groovebehind the rim, the cartridge casingcannot be pushed past the extractor. Instead, the hookfunctions as a pivot point and the cartridge casingis rotated to the side of the extractorand ejected out of the firearm. This particular configuration is for right-handed users, but the positions of the extractorand the case guidecould be reversed such that the cartridge casingis ejected out the other side for left-handed users.

In at least one possible embodiment, the multi-caliber bolt assemblycan be used in essentially any firearm, such as, but not limited to, a slide-operated pistol, a semi-automatic rifle with or without barrel lockup, a bolt-action rifle, a lever-action rifle, semi-automatic and fully-automatic rifles and pistols, and fully-automatic machine guns.

With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of an embodiment enabled by the disclosure, 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 an embodiment of the disclosure.

Therefore, the foregoing is considered as illustrative only of the principles of the disclosure. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the disclosure 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 disclosure. In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be only one of the elements.