Abstract
A bolt for a firearm having a rotatable head and carrier body has a twisted polygonal keyed interface between the head and carrier body. A neck extending rearward from the head presents the keyed interface with a corresponding bore within the carrier body. This construction reduces torque moments between the head and carrier body as compared to prior art bolts. Camming loads on the neck may be constructed with inverses to create space for tolerance and lubricant.
Claims
1. A bolt for a firearm comprising: a. an elongate bolt carrier body having a bore longitudinally positioned along a bolt axis, the bore being helical with a polygonal circumference; b. a firing pin, residing within the bore of the carrier body; c. a bolt head; d. a hollow bolt neck, extending rearward of the head, engaging the bore of the carrier body in a keyed relationship and through which the firing pin also resides; wherein longitudinal interaction of the hollow bolt neck and the elongate bolt carrier body impart a twist on the bolt head.
2. The bolt of claim 1, the firing pin being spring biased.
3. The bolt of claim 2, further comprising a firing pin spring residing towards an aft portion of the bolt carrier body and the firing pin further comprising a reset pin interacting with the bolt carrier body.
4. The bolt of claim 3, the bolt head further comprising a slot with roughly two orthogonal legs and the firing pin further comprising a release pin residing within said slot, wherein twisting of the bolt head relative to the firing pin moves the release pin in relation to the slot.
5. The bolt of claim 1, the hollow bolt neck presenting loads which interface with the bore with inverses therebetween.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 is a front perspective view of a rotary firearm.
(2) FIG. 2 is a partial sectional view of the rotary firearm of FIG. 1.
(3) FIG. 3 is a sectional view of the rotary firearm of FIG. 2.
(4) FIG. 4 is a perspective view of a prior art firearm bolt.
(5) FIG. 5 is a bottom plan view of the prior art bolt of FIG. 4.
(6) FIG. 6 is a top plan view of a firearm bolt representing a preferred embodiment of the invention.
(7) FIG. 7 is a bottom plan view of the firearm bolt of FIG. 6.
(8) FIG. 8 is a side elevation of the firearm bolt of FIG. 6.
(9) FIG. 9 is a front elevation of the firearm bolt of FIG. 6.
(10) FIG. 10 is a rear elevation of the firearm bolt of FIG. 6.
(11) FIG. 11 is a perspective view of an alternate firearm bolt.
(12) FIG. 12 is an alternate perspective view of the firearm bolt of FIG. 11.
(13) FIG. 13 is a perspective view of the fire arm bolt head and body of the bolt of FIG. 6, disassembled.
(14) FIG. 14 is a sectional view of the firearm bolt of FIG. 6, taken along line A-A.
(15) FIG. 15 is a sectional view of the firearm bolt of FIG. 6, taken along line B-B.
(16) FIG. 16 is a sectional view of the firearm bolt of FIG. 6, taken along line C-C.
(17) FIG. 17 is a sectional view of the firearm bolt of FIG. 6, taken along line D-D.
(18) FIG. 18 is a close-up view of the firearm bolt of FIG. 7, taken in circle E.
(19) FIG. 19 is a multi-stage drawing, depicting the timing involved in a firing operation with an alternate firearm bolt.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
(20) With reference now to the drawings, the preferred embodiment of the firearm bolt is herein described. It should be noted that the articles a, an, and the, as used in this specification, include plural referents unless the content clearly dictates otherwise.
(21) With reference to FIGS. 1 through 3, a representational M134 is depicted. As can be seen in FIGS. 1-3, this particular firearm embodiment features six barrels 10 mounted on a rotor 20 driven in turn by a motor 30. Belt-linked ammunition is fed into the weapon by first entering the delinker/feeding system, which strips individual rounds of ammunition from connecting links and advances individual rounds of ammunition onto one of six rotating slots 22 in the rotor, each corresponding to one barrel 10 and each having one bolt 50. Ammunition is advanced along a cam track 12 with the bolt 50 until it is chambered in a barrel 10 and ignited. After which the bolt 50 retracts, releasing the spent ammunition casing for ejection.
(22) Advancement and retraction of the bolt 50 is accomplished by the interaction of a cam roller 52, positioned on the top surface of the bolt, and the helical cam track 12 fashioned in the receiver 14. As the rotor 20 rotates in a circuit, the cam roller 52 follows the cam track 12 and forces the bolt 50 forward or backwards according to where in the circuit the bolt and rotor are positioned. The forward most position for the bolt 50 is located when the bolt is at the top of the rotor 20 while the rearward most position has the bolt 50 at the bottom of the rotor 20.
(23) A prior art bolt, FIGS. 4 and 5, features a bolt head 7 and bolt carrier, or body 2. The bolt head 7 and body 2 interface with one or two rotation imparting cam structures, each comprising a helical cam arm 5 and a corresponding helical cam slot 4. As the bolt head 7 is compressed against the bolt body 2, the cam arm 5 interacts with the cam slot 4 and causes relative rotation to be imparted to the bolt head 2. As the bolt head 7 and body 2 separate, the same cam structure twists the bolt head 7 back into position relative the body 2.
(24) Like prior art bolts, a bolt 50 which may embody the present invention (FIGS. 6-13) may contain the firing pin 54 coaxial with a central axis of the bolt and also may comprise both a body 56 and a head 58, in a rotatable relationship with each other. The head 58 should have a single helical neck 57 insertable, coaxially, within the body 56. The firing pin 54 may be spring biased, such as by a coil spring 53 (FIG. 16) located between it and the rearward most portion of the bolt 50. Such a coil spring 53 could be maintained in position by a stop insert coaxial with the firing pin 54 and a reset pin 51. The firing pin 54 passes through both body 56 and neck 57, with the tip of the firing pin residing within the head 58. The present invention, however, eschews the use of helical cam arms and instead utilizes the neck 57 to impart a twist upon the head 58. This helical neck 57 corresponds with and is keyed to fit a helical bore 55 in the bolt body 56 (FIGS. 13-17). As the neck 57 is forced through the bore 55, the keyed relationship forces the necessary twist in the neck 57 and head 58. The depicted bolt 50 has a neck 57 with six individual camming loads as opposed to one or two, as is used in the prior art. It should be readily understood that other numbers of loads may be used, with fewer loads bearing more torque and more loads reducing the effect of the keying relationship. Six loads provides an adequate load distribution for purposes of the invention and also a good keyed relationship between the neck 57 and body 56. It is therefore preferred to have six loads, but this preference should not be seen as limiting. As can be seen in FIG. 17, the loads may be separated by slight indents or inverses. This structure would then give some mechanical tolerance and serve to leave space in the bolt bore 55 for lubricant.
(25) The firing pin presents a small release pin 59 towards its forward end. This release pin interfaces with an L-shaped slot 60 along a side of the bolt head 58. The L-shaped slot 60 features two roughly orthogonal legs, one in a transverse direction in relation to the bolt axis 62 and one longitudinally along the bolt axis 64. A small aft hole in the bolt body 56 provides space for the reset pin 51 and presents a detent which captures the reset pin 51 as the bolt 50 is compressed (FIG. 18). Otherwise, the shape of the aft hole may be roughly triangular, as shown in FIG. 12, or may be a helical slot, as shown in FIG. 18, or any other suitable shape. A desirable shape for the aft hole would be on that presents the detent, as described, and also allows for some rotational movement of the firing pin 54 after firing, fitting with what is described in the firing process.
(26) The firing process is illustrated in FIG. 19. When in its starting position, the release pin is located in the transverse leg. There is no change in the relationship between the bolt head 58 and body 56 throughout most of the time the bolt 50 traverses the cam track 12. However, as the bolt 50 reaches the forwardmost position, the bolt head 58 stops as the ammunition is chambered in the barrel 12; but, the body 56 continues forward. This continuation drives the body 56 over the neck 57 and imparts a twist on the neck 57 and head 58 due to the helical keyed relationship between the pieces. The body 56 is also driven over the firing pin 54, compressing the spring and wedging the reset pin 51 into the detent of the aft hole, holding the firing pin rotationally static. Due to a slot in the firing pin 54, the firing pin will move over the resent pin 51 and extend outside of the bolt carrier body 56 as the spring 53 compresses. The twist of the keyed interface does force the head 58 to twist in relation to the firing pin 54 (COCKING). The L-shaped slot 60 then rotates in relation to the release pin 59, causing the release pin 59 to traverse the transverse leg until it is positioned in the corner of the L-shaped slot 60 (POINT OF FIRING) and is then freed (FIRING) to move longitudinally along the longitudinal leg. At this stage, the coil spring 53 is released and projects the firing pin 54 forwards so that the tip extends through a port in the bolt head 58 and impinges the ammunition blast cap, causing ignition. Releasing the firing pin 54 also releases the reset pin 51 from the detent, and allows slight rotation of the firing pin 54. The continuation of the bolt 50 along the cam track 12 then retracts the body 56 from the head, reversing the twist and causing the bolt to reset.
(27) Although the present invention has been described with reference to preferred embodiments, numerous modifications and variations can be made and still the result will come within the scope of the invention. No limitation with respect to the specific embodiments disclosed herein is intended or should be inferred.
