US20210003357A1

US20210003357A1 - B.l.t. bolt carrier

Info

Publication number: US20210003357A1
Application number: US17/019,686
Authority: US
Inventors: Claude A. Durham, III
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-09-28
Filing date: 2020-09-14
Publication date: 2021-01-07

Abstract

A bolt assembly is provided for a firearm. The bolt assembly comprises a block adapted to connect to a firearm frame and a bolt carrier adapted to reciprocate within the frame. The bolt assembly comprises a support element between the block and the bolt carrier. The support element is adapted to reciprocate within the frame with respect to the cap and with respect to the bolt carrier. The first and second spaced apart parallel rods are connected to the cap and extending from the cap. The bolt carrier defines a pair of spaced apart bores receiving the rods. A first spring is interposed between the block and the support element, a second spring is received on the first rod, and a third spring is received on the second rod.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation-in-Part of U.S. patent application Ser. No. 15/718,081 filed on Sep. 28, 2017, entitled “B.L.T. BOLT CARRIER,” which claims the benefit of U.S. Provisional Patent Application No. 62/400,826 filed on Sep. 28, 2016, entitled “BLT Bolt Carrier,” and also claims the benefit of U.S. Provisional Patent Application No. 62/906,161 filed on Sep. 26, 2019, entitled “B.L.T. Bolt Carrier,” which are hereby incorporated by reference in their entirety for all that is taught and disclosed therein.

BACKGROUND OF THE INVENTION

Normal AR15 rifles have an extension tube that extends to the rear of the upper receiver and contains the recoil spring. Given the length of the bolt carrier, the recoil spring needs this length to compress and provide an adequate range of motion of the bolt carrier. A disadvantage of a standard AR recoil assembly, the travel of the buffer to the rear of the buffer tube causes the weapon to have more felt recoil due to more mass at the rear of the weapon. While fine for rifles with normal shoulder stocks, the protruding extension tube is a problem for pistol variants of the AR 15, as well as folding or fully collapsing stocks, which are incompatible with a fixed extension tube.
Accordingly, it is desirable to create a shorter bolt carrier that has a recoil spring capability that operates fully within the limited length of an AR-15 upper, with no extension tube. Due to spring resonance of a shorter operating platform, the BCG weight is operating closer to center axis, and less recoil is noticed as muzzle flip is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the B.L.T. Bolt Carrier. The assembly includes a bolt carrier 1 that has opposed linear bores. A top-hat shaped center support 4 has parallel protruding guide rods 2 that extend into the bores so that the center support telescopes with respect to the bolt carrier. The two bores associated with the rods are large enough to receive compression coil springs 16 that bias the center support away from the bolt carrier.
An end cap 5 is threaded 11 to connect to the lower receiver (not shown) on existing threads where a stock might normally be attached, in line with the center of the barrel bore and bolt carrier. The cap essentially becomes the rear wall of the receiver, and the fixed frame of reference that the bolt reciprocates with respect to. A rear spring (coil, compression) 17 is captured between the center support 4 and the cap. Thus, as the bolt reciprocates, the main springs 16 and rear spring 17 both compress, each storing some of the recoil energy for recover for stripping and chambering the next round. The center support 4 floats between the bolt carrier and the cap during recoil cycling, at a middle position between the two.
If a single rear spring were used (as in a conventional AR-15), it would have to be much longer, and the “end cap” would need to be lengthened to become an extension tube. This is partly due to the need to absorb recoil energy, and partly due to the length of the fully collapsed spring when the coils are stacked against each other, a condition normally to be avoided. It is not possible to extend the rear spring forward into or around the bolt carrier because of the needed structure and functions of the bolt carrier. However, the main spring that resides in part within the bolt carrier bore provides this added spring capability without lengthening the rear spring undesirably. The three springs are essentially end to end, and the entire rear spring remains to the rear of the entire front spring in all conditions. These are serially connected with the center support gripped or pinched between them, and each spring has a size and shape based on the space it has to work within the B.L.T. BCG.
In this exploded view, the image shows the rear view of the main spring zero footprint pocket (6), the guide rods (2) that are attached to the center support (4). The end cap is the end of the B.L.T. BCG that houses the solid height of the rear spring.
FIG. 2 shows the installed length with a frontal view looking to the right side to the rear. The B.L.T. utilizes a milspec bolt. The bore is milspec diameter (15).
FIG. 3 shows the installed length with the right side of the B.L.T. BCG. The guide rod bore hole goes through the entire BCG. The end cap shows the threads with a 1 3/16″-16 tpi pitch is how the end cap attaches to the lower receiver.
FIG. 4 shows the view when the B.L.T. carrier is in collapsed position from being fired. In this position, the retention guide rod is showing through the ejection port cutout. The center support recesses internally into the end cap fully compressed.
FIG. 5 shows a top view image looking down on the installed length, ready to fire. This spring technology has zero footprint solid height. The main springs recess internally in the carrier. The rear spring recesses into the end cap.
The rear spring 17 presses on the rear surface of the flange of the center support 4, and the main springs press on the front surface of the flange, guided by the rods.
FIG. 6 shows the B.L.T. Bolt Carrier. The assembly includes a bolt carrier 1 that has opposed linear bores. A top-hat shaped center support 4 has parallel protruding guide rods 2, 3 that extend into the bores so that the center support telescopes with respect to the bolt carrier. The retention guide rod 3 has a flared tip that prevents the center support assembly from falling out of the bolt carrier. The bore associated with rod 2 is large enough to receive a compression coil spring 16 (not shown) that biases the center support away from the bolt carrier.
An end cap 5 is threaded 11 to connect to the lower receiver (not shown) on existing threads where a stock might normally be attached, in line with the center of the barrel bore and bolt carrier. The cap essentially becomes the rear wall of the receiver, and the fixed frame of reference that the bolt reciprocates with respect to. A rear spring (coil, compression) 17 is captured between the center support 4 and the cap. Thus, as the bolt reciprocates, the main spring 16 and rear spring 17 both compress, each storing some of the recoil energy for recovery for stripping and chambering the next round. The center support 4 floats between the bolt carrier and the cap during recoil cycling, at a middle position between the two.
If a single rear spring were used (as in a conventional AR-15) it would have to be much longer, and the “end cap” would need to be lengthened to become an extension tube. This is partly due to the need to absorb recoil energy, and partly due to the length of the fully collapsed spring when the coils are stacked against each other, a condition normally to be avoided. It is not possible to extend the rear spring forward into or around the bolt carrier because of the needed structure and functions of the bolt carrier. However, the main spring that resides in part within the bolt carrier bore provides this added spring capability without lengthening the rear spring undesirably. The two springs are essentially end to end, and entire rear spring remains to the rear of the entire front spring in all conditions. These are serially connected with the center support gripped or pinched between them, and each spring has a size and shape based on the space it has to work within.
In this extended position/installed length is a see through image that shows internal view of the main spring zero footprint pocket (6), the smooth guide rod (2) that is attached to the center support (4) by the threaded end (8), the retention guide rod (3) and the flared tip (7) that is inserted through the carrier from the front to the center support where it is threaded into the center support (4), now the carrier (1), main spring (16), guide rods and center support connected in operational order. The end cap is the end of the B.L.T. BCG that houses the solid height of the rear spring.
FIG. 7 shows installed length showing a frontal view looking to the right side to the rear. The B.L.T. utilizes a milspec bolt. The bore is milspec diameter (15), utilizes milspec dust cover cutout (12).
FIG. 8 shows installed length showing the right side of the B.L.T. BCG, the guide rod bore hole goes through the milspec ejection port cutout. The end cap shows the threads with a 1 3/16″-16 tpi pitch is how the end cap attaches to the lower receiver.
FIG. 9 shows the B.L.T. carrier is in collapsed position from being fired. In this position the retention guide rod is showing through the ejection port cutout. The center support recesses internally into the end cap.
FIG. 10 shows a cutaway view from the bottom looking up in the collapsed position when in recoil from being fired.
FIG. 11 shows a cutaway view from the top looking down in the extended install length ready to be fired.
FIG. 12 shows a top view image looking down on the installed length, ready to fire. This spring technology with zero footprint solid height. The main spring on the left side shows how the spring recesses internally in the carrier. The rear spring recesses into the end cap.
The rear spring 17 presses on the rear surface of the flange of the center support 4, and the main spring presses on the front surface of the flange, guided by the rod 2.
FIG. 13 shows the same view as FIG. 12, but in the fully compressed condition in full recoil. The center support 4 ensures that if a first one of the springs is fully compressed so that the coils touch each other, then the other spring will have some accommodation to limit this “crash” before it can have a harmful effect.
FIG. 14 is fully compressed no springs.
FIG. 15 is a frontal view looking from the left side to the rear.

LIST OF THE PARTS

1. B.L.T. (Bufferless technology) Bolt Carrier
2. Guide Rod Smooth
3. Guide Rod Retention
4. Center support
5. End cap
6. Main spring “zero footprint” pocket
7. Flared end of retention guide rod
8. Threaded guide rod ends
9. Standard Cam cutou
10. Standard gas key cutout
11. End cap threads (standard buffer threads)
12. Standard dust cover cutout
13. Standard Gas stake bolt holes
14. Gas hole
15. Milspec B.C.G. bore hole
16. Main spring
17. Rear spring

DESCRIPTION OF ALTERNATIVE EMBODIMENT(S)

FIG. 16 shows an alternative embodiment of the B.L.T. Bolt Carrier. Some callouts are duplicated from other figures and should be clear with respect to the figure and embodiment being discussed. The assembly includes a bolt carrier 1 that has opposed linear bores. A two-piece top-hat shaped center support 3 & 4 has a rear bump stop 7 and internal bump stops 8 with parallel protruding guide rods 2 that extend into the bores so that the center support telescopes with respect to the bolt carrier. The bores associated with rod 2 is large enough to receive a compression coil spring 16 (not shown) that biases the center support away from the bolt carrier. In addition, a recoil catch 14 attaches into the upper receiver (not shown) to prevent overtravel and stopping recoil assembly in correct position.
An end cap 105 is threaded 11 to connect to the lower receiver (not shown) on existing threads where a buffer tube might normally be attached, in line with the center of the barrel bore and bolt carrier. The cap essentially becomes the rear wall of the receiver and the fixed frame of reference that the bolt reciprocates with respect to. A rear spring (coil, compression not shown) 17 is captured between the center support 3 & 4 and the end cap 5. Thus, as the bolt reciprocates, the two main springs 16 and rear spring 17 both compress, each storing some of the recoil energy for recovery for stripping and chambering the next round. The center support 3 & 4 floats between the bolt carrier and the end cap during recoil cycling, at a middle position between the two.
Additionally, a slide weight 13 secured to the bolt carrier via carrier gas key 10 or other means of attachment if the BCG has an integrated gas key (not shown) spring-loaded to absorb energy in both directions of travel, slowing the opening time when a round is fired, and securing proper lockup into battery.
If a single rear spring were used (as in a conventional AR-15), it would have to be much longer, and the “end cap” would need to be lengthened to become an extension tube. This is partly due to the need to absorb recoil energy, and partly due to the length of the fully collapsed spring when the coils are stacked against each other, a condition normally to be avoided. It is not possible to extend the rear spring forward in to or around the bolt carrier because of the needed structure and functions of the bolt carrier. However, the main springs that resides in part within the bolt carrier bore provides this added spring capability without lengthening the rear spring undesirably. The two main springs in parallel are essentially stacked on the rear spring, and entire rear spring remains to the rear of the entire front springs in all conditions. These are serially connected with the center support gripped or pinched between them, and each spring has a size and shape based on the space it has to work within.
In this extended position/installed length is an image that shows a top side view of the main spring zero footprint pocket (6) that can extend through the slide weight (13), the smooth guide rod (2) that is attached to the center support (3 & 4), that is inserted through the slide weight (13) and the carrier (1). The end cap is the end of the B.L.T. BCG that houses the solid height of the rear spring. To secure stocks, braces or any type of attachments, an adapter (20 & 21) secured to the back of lower receiver (not shown) is attached by the end cap (5) securing adapter mounting plate (21) to the lower receiver, and rail adapter (20) attaching to adapter mounting plate.
FIG. 17 shows the installed length with a frontal view looking from the right side to the rear. The B.L.T. utilizes a milspec bolt (15). The bore is milspec diameter and utilizes a milspec carrier gas key (10). Internal center support bump stops (8) are made of polymers and polyurethane
FIG. 18 shows the installed length with a frontal right side to the rear view of the B.L.T BCG with installed main springs (16) and rear spring (17).
FIG. 19 shows when the B.L.T. carrier (1) is in the collapsed position from being fired, the center support recesses internally into the end cap (5).
FIG. 20 is an exploded right side view, and all components listed are shown.
Firing pin plunger (12) has a spring attached (18) that is secured by the milspec retainer pin (not shown), keeping pressure outward on the standard milspec firing pin (20) away from the primer of the ammunition.
FIG. 21 is an exploded view of the right side showing all components minus springs. The end cap shows that threads with a 1 3/16″-tpi pitch is how the end cap attached to the lower receiver.
FIG. 22 is an exploded frontal view looking from the right side to the rear, and all components listed are shown.
FIG. 23 is an exploded rearward view looking from the right side to the front, and shows all components listed minus springs.
FIG. 24 is a right side view of the B.L.T. bolt carrier (1) with slide weight (13) fully collapsed.
FIG. 25 is a right side top frontal view of the B.L.T. bolt carrier (1) with slide weight (13) fully collapsed showing the linear path (23) the slide weight travels from open to collapsed. The slide weight is secured by the carrier gas key or other means if the carrier has an integrated gas key or a modified gas system.
FIG. 26 is a right side view of the B.L.T. bolt carrier (1) with slide weight (13) in the open position. In this position, the spring pressure (19) keeps the slide weight away from the bolt carrier between 0.15″-0.25″ depending on the application (caliber, barrel length, suppressed or un-suppressed). When a round is fired, the bolt carrier moves rearward and the slide weight spring compresses, closing the gap between the slide weight and bolt carrier. When the bolt carrier impacts the slide weight, the slide weight slows the carrier. When the bolt carrier (1) is returning to battery, stripping the next round from the magazine (not shown), the spring pressure (19) returns the slide weight to the open position. When the bolt carrier (1) and bolt (15) lock into battery, the slide weight follows forward from the inertia (compressing the spring for the slide weight) to the closed position impacting the bolt carrier (1), thus giving a dead blow effect to the bolt carrier thereby ensuring proper lockup and reducing bolt bounce.
FIG. 27 is a right side top frontal view of the B.L.T. bolt carrier (1) with slide weight (113) at the open, resting position. This image shows the linear path (23) of how the slide weight travels from open to closed.
FIG. 28 is a right side cross-section view of the installed length, minus springs.
FIG. 29 is a right side cross-section view of the installed length, showing springs. Length is conserved by telescoping the springs within the length of the bolt carrier (101), so that they bear near the front of the bolt carrier.
FIG. 30 is a right side cross-section view fully collapsed in the fired position minus springs.
FIG. 31 is a right side cross-section view fully collapsed in the fired position with springs.

LIST OF THE PARTS

1. B.L.T. (bufferless technology) Bolt Carrier
2. Guide Rod
3. Center support front
4. Center support rear
5. End cap
6. Main spring “zero footprint” pocket
7. Rear center support bump stop
8. Internal center support bump stops
9. Milspec cam pin
10. Milspec carrier gas key
11. End cap threads (milspec buffer tower threads)
12. Firing pin plunger
13. Slide weight
14. Recoil assembly catch
15. Milspec bolt
16. Main springs
17. Rear spring
18. Spring, firing pin plunger
19. Spring, slide weight
20. Milspec firing pin
21. Adapter interface
22. Mount, adapter interface
23. Linear path, slide weight

Claims

The claimed invention is:

1. A bolt assembly for a firearm comprising:

a block adapted to connect to a firearm frame;

a bolt carrier adapted to reciprocate within the frame;

a support element between the block and the bolt carrier;

the support element adapted to reciprocate within the frame with respect to the cap and with respect to the bolt carrier;

a rod connected to the cap and extending from the cap;

the bolt carrier defining a bore receiving the rod;

a first spring interposed between the block and the support element; and

a second spring received on the rod.