US2883782A - Automatic shotgun choke - Google Patents

Description

INVENTOR.

Aim/ways.

April 28, 1959 A. E. SCHROEDER AUTOMATIC SHOTGUN CHOKE Filed Jan. 25, 1956 Ar/a' Jab/v60???" BY United States Patent AUTOMATIC SHOTGUN CHOKE Arlo E. Schroeder, Newton, Kans. Application January 25, 1956, Serial No. 561,263 Claims. (Cl. 42-79 This invention relates to new and useful improvements in shotguns, and has particular reference to the devices used in connection with shotguns and commonly designated as chokes, which are devices used to reduce the area of the shot pattern of the gun.

The principal object of the present invention is the provision of a choke which is adjustable from an unrestricted or open-choke setting to a relatively restricted or full-choke setting, and which will advance from said open-choke setting to said full-choke setting automatically after the gun is fired. In firing at birds or other moving targets which normally move farther away from the gunner if not hit by the first shot, it is desirable that the choke be restricted on successive shots, whereby to reduce the shot pattern so that it will retain its effectiveness and hitting power at greater distances. The adjustment must be automatic and rapid, since the gunner commonly does not have sutficient time in which to make the adjustment manually. It will be obvious that the full-choke setting referred to above is relative only, and may if desired actually be on intermediate or modified choke.

Another object is the provision of an automatc shotgun choke of the character descrbed wheren the adjustment is accomplished automatically by the force of recoil when the gun is fired.

A further object is the provision of an automatic shotgun choke of the character described which may be moved manually to either setting desired, and locked in either of said settings in the event automatic operation v is not desired.

Other objects are extreme simplicity and economy of construction, efliciency and dependability of operation,

. and adaptability for use with shotguns of virtually any choke position,

Fig. 3 is a fragmentary view similar to Fig. 2, show ing the choke in the full-choke position, and

Fig. 4 is a sectional view taken on line IVIV of Fig.- 2.

Like reference numerals apply to similar parts throughout the several views, and the numeral 2 applies to the barrel of a shotgun, only the forward end portion of said barrel being shown. The choke mechanism, designated generally by the numeral 4, is mounted at the forward end of said barrel. Said choke mechanism incorporates a cylindrical tubular body 6 which is disposed coaxially with and forms a forward extension of barrel. The rearward end portion 8 of said body member is enlarged and internally threaded for connection with body shoulder 18 and notch 33 formed in block threads formed externally on the barrel, said threaded connection being designated at 10. Obviously a soldered or other permanent or detachable rigid connection could be used instead of the threads if desired.

The forward end portion of the choke body has a plurality of slits 12 formed longitudinally therein at regularly spaced circumferential intervals, thereby forming a plurality of longitudinally projecting tongues 14. The

material of the body member is sufliciently resilient that said tongues may be deflected inwardly, as will be described, to restrict the diameter of the forward end portion of the body member. desired yieldaliility of the tongues, the body member may be weakened at the base of said tongues by grooving the body member peripherally, as at 16.

Adjacent its rearward end, body member 6 is provided with an external peripheral shoulder 18, whereby the diameter of said body member is increased. Threaded or otherwise fixed to said portion of increased diameter is the rearward end of a housing tube 20, said housing forming an annular chamber 22 therebetween. Said housing extends flush with the forward end of the body,

and is provided at its forward end with an internal peripheral flange 24, the inner edge of said flange engaging tongues 14 of the body in their normal or expanded position, whereby to limit their outward move,- ment. Body member 6 is provided adjacent its forward end with an external, rearwardly facing bevelled shoulder 26 extending peripherally therearound. Said shoulder is of course carried by the tongued portion of the body, but is disposed in rearwardly spaced relation from housing flange 24.

An inertia block 28 having the form of a cylindrical tube is disposed in annular chamber 22, having sliding engagement both with body member 6 and housing 20, and is normally disposed between shoulders 18 and 26 of the body member. It is provided at its forward end with a peripheral cam face 30 bevelled correspondingly to shoulder 26 of the body member, said shoulder acting as a cooperating cam member. Said bevelled face is urged toward said shoulder by a coil spring 32 disposed in annular chamber 22 behind inertia block 28 and urging said block forwardly, said spring bearing at its rearward end against shoulder 18 and at its forward end against a shoulder 34 formed externally on the inertia block. Said spring is also maintained in torsional stress as will appear, the extreme end portions 29 of said spring being bent to extend parallel to the axis of the spring and being retained respectively in a notch 31 formed in shoulder 34.

A short latch pin 36 is threaded fixedly in inertia block 28, and extends radially downwardly therefrom through a cooperating latch slot 38 formed longitudinally in housing 20. Said slot is provided at one side thereof with a pair of lateral notches 40 and 42 into which pin 36 may be moved, notch 42 being disposed at the extreme forward end of slot 38 so as to receive pin 36 when inertia block 28 is in its extreme forward or choking position, and notch 40 being disposed rearwardly from notch 42 so as to receive pin 36 when block 28 is sufliciently far to shoulder 26. At the side of slot 38 opposite notches 40 and 42, slot 38 is provided with a third lateral notch 41 adapted to receive pin 36. The forward edge of notch 41 is notched forwardly to form a rearwardly opening socket 43 which serves to prevent angular movement of pin 36 when said pin is disposed therein. The rearward edge of notch 41 is bevelled as at 45. Spring 32 is tensioned so as to urge inertia block 28 rotatively' in a counter-clockwise direction, looking forwardly so as to Patented Apr. 28, 1959 If necessary to provide the aesspsa urge. pin 36? toward the side of slot 38 having notches 40 and 42 formed therein.

The operation of the choke is substantially as follows: Assuming first that latch pin 36 has been manually moved into. notch 41 and. forwardly into.- socket. 43 thereof, the parts then have the position shown. in Fig, 2. Sincecam face 30 of inertia block 28 is. disposed. rearwardly of cam shoulder 26 of. the body member, body member tongues 14 are expanded by their own. resilience to their open-choke position. Pin 36. is prevented from being twisted out of notch 41. into slot. 38. by the torsion of spring 32, due to. the. inclusion. of. said pin in socket 43 of. notch 41.

When the gun isv fired, the gun. and choke of course recoil sharply, and. the. choke housing, acting on latch pin. 3.6, forces. inertia block: 28 to. travel rearwardlly with.

the. choke body. Thus the cams 26i-30. cannot. operate: on direct recoil. This delay of. the cam. action isv essen.-- tial since the recoil movement begins before the charge of. shot reaches. the end of the barrel, and direct action of. the. cams would result. in choking of the gun even on. the first shot. When the recoil of the gun is stopped, orat. least. retarded, by the gunners shoulder, inertia block 28. continues tomove rearwardly by its ownv momentum, compressing. spring 32. The rearward movement of said block disengages pin 36 from socket 43 of. notch 41,. and causes said pin to impinge sharply on the bevelled rear- Ward edge 45 of the notch. Said bevel acts. as a cam, forcing said pin outwardly from notch 41 into slot 38. The positive action ofbevel 45 is also assisted by the torsional tension of spring 32, which tends to turn said pin into slot 38. Said spring also serves to. hold. said pin in slot. 38, preventing: any possibility that, said. pin might. re enter notch 41 on. forward movement; of the inertia block. Said. inertia block is forced forwardly by spring 32. after said spring has absorbed the. momentum-of the; block. During the forward movement of the block, pin 36 by-passes notch 41, permitting engagement of cam face 30. of the. block with. cam shoulder 26 of the body, said block. overriding said. shoulder thereby contracting tongues 14 inwardly to their full-choke? position, the parts then having the position shown in. Fig. 3. By the time cams 26-30 function, the. recoil is completed and the. charge has cleared the end. ofthe choke and there is no danger of operating the choke prematurely. In this sense, it may be said that the latch. means, though. recoil operated, incorporates a time-delay actionprevent. ing operation of the cams tillv the recoil has. been. completed.

During. the. forward, movement of pin 36,, it. moves with sufficient speed that: it' by-passes and doesnot enter notch.- 40, despite the torsional. stress of' spring 32. However, to prevent battering. of the; forward edge of. notch. 40 by the. pin, the. tongue of. metaL 47 between. notches 40 and 42' may be. shortened, as clearly shown. inFig. 1.. Body flange 24 arrests the forward movement of. the block, and spring. 32 immediately functions to turn. pin 36 into notch 42, thereby. locking the. choke. in its re-- stricted position. On all subsequent shots, therefore, the

choke will remain. in itsv restricted. position, until such.

time. as pin 36.. is.manually'moyed.intosocketr43. of. notch 41. Also,.the choke may be. locked in its. open position by moving pin 36 manually. intonotch 40,v and will re.- main open through any number of shots. Pin 36 may of course be moved into either of. the. locking notches. 40 or 42 at. any time. desired, and. will. be; retained therein. by. spring; 32.

Housing 26 acts: as a; guide. for the: inertia. block, in. suring; straight:v travel. of". said. centering; thereof relative to body shoulder 26. also. permits the. in.

terchangeableuse. in. the choke. of inertia blocks; off-differ. ent internal diameters. of the degree of barrel restriction actually provided. by

the choke, both in its. relatively; open. and relatively re;-- striated.positions.v It: will. besnntedtalso, that the:

This permits ready adjustment.

block is sufli'ciently long to extend rearwardly of the body slits 12, even when said block is in its forwardmost position, thereby in large measure preventing leakage of explosion gasses into chamber 22. This reduces the danger of fouling the mechanism, and also reduces the frequency with which the mechanism must be cleaned.

While I have shown and described a specific embodiment of my invention, it will be apparent that many modifications of structure and operation could be made without departing from. the spirit of: the invention as defined by the scope of the appended claims.

What I claim as new and desire to protect by Letters Patent. is:

1. An automatic shotgun choke comprising a body member adapted to be secured to a shotgun barrel to form a forward extension thereof, and having a resiliently contractile section operable to be restricted to reduce the internal diameter thereof, a tubular housing concentric. with said body member, being fixed to a rigid. portion of said body member and forming an annular chamher around said contractile section, said housinghavinga. slot formed longitudinally therein, anv inertia block in the form of a cylindrical tube; carried in said annularchamber for forward, rearward and rotary movement, said contractile body section and said inertia block having cooperating cam surfaces formed thereon andv operable by forward movement of said inertia block fromv a normal. position to restrict said contractile body section, a spring carried in said annular chamber and urging said inertia block forwardly, and a pin fixed in said inertia block and, extending radially through said housing slot,

said slot having a side notch formed therein adapted toreceive said pin, the forward wall of said. slot being,

cam said pin transversely into said slot when. said inertia block recoils' relative to said. housing.

2. A choke as recited in claim 1 wherein said housingslot. is provided with. a pair of additional side notches formed. therein, the rearward edges of said additional notches being disposed in. planes at right angles to theaxis of the body member, said pin being selectively movable into either of said notches whereby to lock said inertia block either in its normal position or in a forward position in which saidcontractile body section. is restricted.

3. An. automatic shotgun choke comprising a body member adapted to be secured to a shotgun barrel. to form a forwardextension thereof, andhaving a resiliently contractile section operable to be restricted to reduce; the. in, ternal diameter thereof, a tubular housing concentric. with. said body member, being fixed to a rigid portion of said body member and forming an annular chamber around said contractile. section, said housing, having a slotformed. longitudinally therein, an inertia. block: in the form of; a cylindrical tube carried in said annular chamber for forward, rearward and rotary movement, said contractile body section and saidinertia block having cooperating. cam surfaces formed thereon and operable by forward movement: of: said inertia block from a normal position. to restrict said contractile body section, a spring carried. in said annular chamber and. urging said inertia block forwardly, anda pin fixed in said inertia block and extending radially through said housing slot, said slot having. a side notch formed therein adapted to receive said pin, the forward. wall of said slot being socketedto. prevent transverse moyement' of the. pin when said. pin. positioned.

therein, said inertia. block being: then in its. normal position longitudinallyof. the: choke body, and. the rearward.

wall. of. saidnotch being; bevelled whereby tocant said.

pin transversely into said slot when said inertia block reinto said slot when said inertia block recoiis relative to said housing.

4. An automatic shotgun choke comprising a body member adapted to be attached to a shotgun barrel to form a forward extension thereof, and having a contractile section operable to be restricted to reduce the internal diameter thereof, an inertia member carried by said body member for forward and rearward movement from a normal position relative thereto, said inertia member and said body member having cooperating actuating members formed thereon and operable by forward movement of said inertia member to restrict said contractile section, resilient means urging said inertia member forwardly, a member fixed to said body member and having a slot formed therein parallel to the axis of said body member, a pin fixed in said inertia member and extending transversely through said slot, said slot having a side notch into which said pin may be moved to lock said inertia member in its normal position against forward movement, the forward wall of said notch being socketed to receive said pin to prevent lateral movement thereof into said slot, whereby said inertia member is forced to recoil rearwardly with said body member when said gun is fired,

said inertia member continuing to move rearwardly against said resilient means by its own momentum after the recoil movement of said body member is substantially completed, and the rearward wall of said notch being bevelled, whereby on rearward movement of said inertia member relative to said body member, said pin will engage said bevelled notch wall and be cammed thereby into said slot.

5. An automatic shotgun choke as recited in claim 4 wherein said resilient means, in addition to urging said inertia member forwardly, is also tensioned to urge said pin transversely out of said notch into said slot, whereby to assist the cam action of the bevelled wall of said notch, and to prevent re-entry of said pin into said notch during forwardly movement of said inertia member.

References Cited in the file of this patent UNITED STATES PATENTS 685,669 Broyles Oct. 29, 1901 1,508,605 Legett et al Sept. 16, 1924 2,417,721 Whedon Mar. 18, 1947 2,685,144 Schroeder Aug. 3, 1954 2,759,286 Moore Aug. 21, 1956

Images