Bolt mechanism for fire arm

• US 4,893,547 A
• Filed: 09/14/1987
• Issued: 01/16/1990
• Est. Priority Date: 12/31/1981
• Status: Expired due to Term

• Current Assignee: Maxwell G. Atchisson
• Original Assignee: Maxwell G. Atchisson
• Inventors: Atchisson, Maxwell G.
• Primary Examiner(s): Bentley, Stephen C.
• Application Number:
  US07/096,934
• Time in Patent Office: 855 Days
• Field of Search: 89/165, 89/173, 89/187.01
• US Class Current: 89/187.01
• CPC Class Codes: F41A 11/00 Assembly or disassembly features; Modular concepts; Articulated or collapsible guns F41A3/64, F41A19/10 - F41A19/15, F41A21/48, F41A25/26 take precedence
• CPC Class Codes: F41A 15/12 for bolt-action guns
• CPC Class Codes: F41A 17/46 Trigger safeties, i.e. means for preventing trigger movement F41A17/02 - F41A17/40 take precedence
• CPC Class Codes: F41A 19/46 Arrangements for the selection of automatic or semi-automatic fire
• CPC Class Codes: F41A 3/46 mounted on the bolt F41A3/48 takes precedence
• CPC Class Codes: F41A 3/72 Operating handles or levers; Mounting thereof in breech-blocks or bolts F41C7/02, F41C7/06 take precedence
• CPC Class Codes: F41A 5/18 gas-operated
• CPC Class Codes: F41G 1/06 Rearsights

Abstract

A locked breach, gas operated long action firearm capable of firing heavy caliber shotgun or rifle shells with substantially reduced recoil. The gas piston and bolt carrier assembly are supported for recoil movement along a single guide rod which extends the entire length of the gun, permitting a longer recoil path resulting in reduced impulse due to recoil. The guide rod has a noncircular or radially-assymmetrical cross-section mating with a corresponding opening in the gas piston, so that the bolt carrier assembly remains in alignment over the entire recoil path. Separate close-bolt and open-bolt embodiments are disclosed, and the open-bolt embodiment is selectively capable of firing either semi-automatic or full-automatic while permitting reliable cartridge feeding from a box or drum magazine.

Claims

1. Bolt locking mechanism for a firearm including a breech, comprising:

a bolt carrier selectively movable on a predetermined path;

a bolt movable with the bolt carrier either to a forward position relative to the breech of the forearm, or to a rearward position, the bolt carrier being associated with the bolt to allow the bolt carrier a limited extent of forward travel beyond the forward position of the bolt;

cam means associated with the bolt carrier and extending longitudinally of the bolt carrier;

the bolt having a hollow portion within which the cam means moves as the bolt carrier travels relative to the bolt;

lock means movable with the bolt and operable by said cam means, in response to the limited extent of forward travel by the bolt carrier, to move vertically relative to the bolt on a path normal to the path of bolt movement, so as to extend upwardly from the top of the bolt and engage the breech, locking the bolt in the forward position;

the lock means being disposed in the hollow portion of the bolt;

the lock means including surfaces defining a window extending within the hollow portion of the bolt along a path generally parallel to the path of bolt movement, and receiving the longitudinally-extending cam means in operative relation with the window-defining surfaces,

so that the cam means moves the lock means vertically to lock or unlock the bolt as the cam means moves longitudinally within the window in the hollow portion of the bolt.

2. Bolt locking mechanism for a gas-operated firearm having a barrel, a magazine-receiving well disposed below a breech end of the barrel to receive a magazine for feeding rounds upwardly into the breech end, a gas piston assembly located above the barrel, and a side ejection means at a side of the breech for ejecting spent shells, comprising in combination:

a bolt carrier selectively movable on a predetermined path relative to the breech;

a bolt movable with the bolt carrier either to a forward position relative to the breech of the firearm, or to a rearward position, the bolt carrier being associated with the bolt to undergo a limited extent of forward travel beyond the forward position of the bolt;

a barrel extension secured to the breech end of the barrel and receiving the bolt in forward position, the barrel extension having a lower side comprising a cartridge feed ramp located immediately in front of the magazine well and sloped upwardly to assist in feeding shells from the magazine into the breech;

the barrel extension having a top surface located below the gas piston and above the bolt in forward position, with a hole formed in the top surface in confronting relation to the top of the bolt;

the bolt having a hallow passage with a vertical axis aligned with the axis of the barrel extension hole when the bolt is in forward position;

a bolt lock member slidably disposed in the bolt passage for selective vertical movement therein;

the bolt having a open interior region substantially parallel to the path of travel of the bolt and intersecting the bolt passage, such that the bolt lock member is partially within the open interior region;

the bolt lock member having first and second cam follower means within the interior region;

a cam member on the bolt carrier and extending longitudinally into the interior region of the bolt;

the cam member having a first cam surface coacting with the first cam follower means on the bolt lock member to move the bolt lock member upwardly into engagement with the hole in the top surface of the barrel extension when the bolt carrier undergoes forward travel beyond the forward position of the bolt, thereby locking the bolt within the breech;

the cam member having a second cam surface coacting with the second cam follower means on the bolt lock member to move the bolt lock member downwardly out of engagement with the hole in the top surface of the barrel extension when the bolt carrier travels rearwardly relative to the bolt, thereby unlocking the bolt for rearward travel with the bolt carrier;

the bolt lock member having a window having an extent substantially perpendicular to the vertical movement of the bolt lock member;

the window being within the open interior region of the bolt, and having upper and lower extent comprising the first and second cam follower means; and

the cam member comprises an elongate element extending forwardly of the bolt carrier to enter the window, and having said first and second cam surfaces on upper and lower portions of the elongate element in confronting and coacting relation with the upper and lower extents of the window.

3. Bolt locking mechanism for an autoloading firearm including a breech, a magazine mounted below the breech for feeding rounds upwardly, and a side ejection port for ejecting spent shells, comprising in combination:

a bolt carrier selectively movable on a predetermined path relative to the breech;

a bolt movable with the bolt carrier either to a forward position relative to the breech of the firearm, or to a rearward position, the bolt carrier being associated with the bolt to undergo a limited extent of forward travel beyond the forward position of the bolt;

a hallow passage formed in the bolt and defining a generally vertical axis;

lock means disposed in the hollow passage and selectively slidable therein along the vertical axis between upper and lower positions;

lock engaging means located above the bolt in the forward position and disposed in fixed relation to the breech, said lock engaging means being engaged by the lock means in the upper position to lock the bolt in the forward position;

cam means associated with the bolt carrier and extending into the bolt for operative engagement with the lock means;

the cam means having an upper cam surface contacting a mating first cam follower surface on the lock means to move the lock means upwardly and lock the bolt in the forward position, when the bolt carrier undergoes the limited extent of forward travel beyond the forward position of the bolt;

the cam means having a lower cam surface contacting a mating second cam follower surface on the lock means to move the lock means downwardly and unlock the bolt as the bolt carrier travels rearwardly said limited extent relative to the bolt;

the cam means comprising an elongated finger extending forwardly of the bolt carrier; and

the lock means having a window extending therein along a path perpendicular to said vertical axis and receiving the elongate finger for movement within the window as the bolt carrier travel forwardly and rearwardly relative to the bolt.

4. Apparatus as in claim 3, wherein:

the elongated finger has an upper side angled to define the upper cam surface and a lower side angled to define the lower cam surface; and

the windows of the lock means has upper and lower surfaces selectively engaging the upper and lower cam surfaces of the elongate finger.

5. Apparatus as in claim 3, wherein:

the elongated finger has an upper side with a first ramp surface angled relative to the path of travel of the bolt carrier and engaging a mating angled follower surface at an upper end of the window in the lock means, so as to move the lock means upwardly within the passage in the bolt and into the lock engaging means as the bolt carrier moves forward a first portion of the forward travel relative to the bolt; and

the upper side having a second surface comprising a holding surface longitudinally spaced from the first ramp surface and substantially parallel to the travel path of the bolt carrier, the holding surface moving into engagement with a complementary holding surface spaced on the upper end of the window from the angled follower surface thereon as the bolt carrier moves forwardly beyond the first portion of forward travel relative to the bolt,

thereby holding the locking means in the upper position engaging the lock

6. Apparatus as in claim 5, wherein:

the elongate finger has a lower side with a second ramp surface angled relative to the path of travel of the bolt carrier and engaging a mating angled second follower surface at a lower end of the window in the lock means, so as to move the lock means downwardly within the passage in the bolt and out of engagement with the lock engaging means as the bolt carrier moves rearwardly a first portion of the rearward travel relative to the bolt;

the lower side having a second surface comprising a second holding surface longitudinally spaced from the second ramp surface and substantially parallel to the travel path of the bolt carrier, the second holding surface moving into engagement with a complementary second holding surface spaced on the lower end of the window from the second follower surface thereon as the bolt carrier moves rearwardly beyond the first portion of rearward travel relative to the bolt,

thereby holding the locking means in the lower position out of engagement with the lock engaging means as the bolt undergoes further rearward travel with the bolt carrier.

7. Bolt locking mechanism for an autoloading firearm including a breech, a magazine mounted below a breech for feeding rounds rearwardly, and a side ejection port for ejecting spent shells, comprising in combination:

a bolt carrier selectively movable on a predetermined path relative to the breech;

a bolt movable with the bolt carrier either to a forward position relative to the breech of the firearm, or to a rearward position, the bolt carrier being associated with the bolt to undergo a limited extent of forward travel beyond the forward position of the bolt;

a hollow passage formed in the bolt and defining a generally traverse axis in relation to the travel of the bolt;

lock means disposed in the hollow passage and selectively slidable therein along the transverse axis between outer and inner positions;

lock engaging means located transversely alongside the bolt in the forward position and disposed in fixed relation to the breech, said lock engaging means being engaged by the lock means in the outer position to lock the bolt in the forward position

cam means associated with the bolt carrier and extending into the bolt for operative engagement with the lock means;

the cam means having an outer cam surface contacting a mating first cam follower surface on the lock means to move the lock means outwardly and lock the bolt in the forward positions, when the bolt carrier undergoes the limited extent of forward travel beyond the forward position of the bolt;

the cam means having an inner cam surface contacting a mating second cam follower surface on the lock means to move the lock means inwardly and unlock the bolt as the bolt carrier travels rearwardly said limited extent relative to the bolt;

the cam means comprising an elongated finger extending forwardly of the bolt carrier; and

the lock means having a window extending therein along a path perpendicularly to said transverse axis and receiving the elongate finger for movement within the window as the bolt carrier travels forwardly and rearwardly relative to the bolt.