US2977702A - Choke with contacting finger and sleeve surfaces of concentric arcs - Google Patents

Description

April 4, 1961 E. SCHACHT 2,977,702 CHOKE WITH CONTACTING FINGER AND SLEEVE SURFACES OF CONCENTRIC ARCS Filed June 8, 1954 FICEZ IN VEN TOR. Emma Same/1r Arm/ways ment of the sleeve.

l atented Apr. 4, 1961 vices, frequently referred to as variable chokes, normally comprise a tubular shell member fixed to the barrel and having'a forward portion adapted to be contracted and expanded to vary the bore diameter of the muzzle end of the barrel. The shell has a plurality of annularly arranged resilient wall segments at its forward end with an adjusting sleeve around the segments for opening or closing the same relative to each other. ,This is conventionally eflected by forwardly taperingthe outer surfaces of the segments and providing atapered mating surface on the sleeve interior sothat contraction and expansion of the choke opening is controlled by longitudinal move- Examples'of this construction are very common in the art. r I

In conventional chokes using the tapered shell such as above mentioned it is necessary that the adjusting sleeve engage the shell segments only along their extended end portions leaving a space between the sleeve and the se gments along their inner portions. So constructed the segments do not have adequate backing and become distorted in time rendering the shell ineffective for governing the shot pattern.

' 'Where the tapered shell and cooperating sleeve are used a'full backing of the segments by the sleeve proves inoperative; This is due to the fact that when the sleeve is adjusted inwardly to close the choke the sleeve will exert inward radial pressure only upon theinner= or rearward portions-of the forwardly extending shell segments leaving their extendedends contracted to a position where they are spacedinwardly from ahdunb'acke'd by the adjustment sleeve. This is due to the fact that the -straight taper'will attempt to move each segment inwardly the same distance along its entire length'while the shell construction demands thatto bringaboutthe choke the extended or forward end portions of the seg- 'ments' must; s V 7 than ;the'i'nner "or rearward portions thereof.

move radially inward a greater distance x'Forth'ese reasons, heretofore known variable choke constructions have failed to provide for rigid shell segthe ctive"nece'ssitatingrepair J I: V s accordinglyv the primary object ofmy invention f'to --provide an 'irnpi'ove'd adjustable fchoke construct kin" gr ri'shetguns whereiii' ,the segmentsofthe choke shell'will "have-complete and adequate-backingregardless of the j 1adjustmentgofthe chokeopening; i

.-...Another.. object of the invention? is-topmvide ia ishot pattern control device; for shotgunswhich will-maintain durable and yet which is simple in design allowing its manufacture at a relatively low cost.

With the above mentioned objectives in mind, my invention broadly comprises forming the exterior surface of the choke shell segments to curve longitudinally inward toward the forward end thereof, said curve being the arc of a circle, and the interior of the adjustmentsleeve having a mating curved surface in flush engagement with said exterior surface of the shell whereby as the sleeve is adjusted longitudinally on the shell the seg ments will be constantly backed throughout their length bythe sleeve.

The above mentioned and still additionalobjects will be brought to light during the course of the following specification, reference being made to the accompanying drawing, in which:

Fig. 1 is a top plan view of my improved shot pattern control device fixed on the end of a shotgun barrel.

Fig. 2 is a longitudinal section of the device taken on line 2-2 of Fig. 1 and showing the choke shell in fully open condition.

' Fig. 3 is a longitudinal section similiar to Fig. 2 with the choke shell in contracted or full choke condition.

Fig. 4 is a transverse section taken on Knee-4 of Fig.2. a

Referring now more particularly to the drawing, reference'numerals will be used to denote like parts or structural features in the different views. The muzzle or discharge end of a shotgun barrel is designatedby the number 5. I have shown my improved shot pattern control device mounted on the barrel end 5, though it is possible to form the shell member, denoted generally at 6, of the device integral with the barrel if desired. The shell 6 is of generally tubular shape and is fixed t0 the barrel in axial'alignment therewith in. any suitable detail. It has a coller' 10 at its inner or rear end adapted of the shell.

manner as by soldering or screw threading. The numher 7 indicates generally a cylindrical adjustment sleeve which fits around the sleeve 6 and which isconnected thereto by suitable means, to be later. described, allowing the sleeve to be longitudinallyadjusted thereon.

In Fig 'l .there is shown a compensator of sleeve 8 7 threaded on the forward end of sleeve 7." This cornpensator 8 provides a conventional expansion chamber" at the forward end ofthe gun barreland has a series of slots 9 therein to allow: escape of the expanding gases following the I discharged shot mass. [he member -S forms no part of the presenhinvention and is tf'shown merely as exemplary of a mannerin which this desirable feature can be employed in connection with th'el'n ovel choke device hereindisclosed. 1

The inner .shell ,6 will now be described in greater to fit: snugly aronntl the barrel fopattaizhment thereto. 1 Forward ofthe collar 10 the shell has'a. reduced internal diameter which is. equalto that of the gun barrel bore.

There is a solid annular portion 11' disposedbetweien the collar, 10 and the forwardconstrictable choke portion 12/ I u Choke portion 12 haslongitudinal slots 14 extending rearwardly from the forward. end {of theshell which divide the portion 12"intoj a plurality'of annularly arranged forwardly extending segmentsa or fingers'15. Therear end of the ichokeportion 12' is fprovided with' a peripheral r v '0 ts accuracy without repair throughout long periods of I I'us "-2 external channel" or groove 13, thepnrpose of which is to reduce thethickness ofthe shellwall at at pai 1'9 OW- he e ment .15 o resiliently" e ed seat 19, the threads 17. and fIQbeing in screwthreadf ling. fil jgcmcut with i each oth er This rnean'sf allows ftotation of the 'slecvfeon thcjshell for, longitudinal adjust- I i them.- Slits 14 ann al-any :wide: to new a limited I amount of such radial movenicntofall of the segments i z 'simultaneously for contraction of; the choke .portion of;

i i h l-- -:"'I I i l The external contour of the choke portion ,12 and the f I 3 I 1 segments 15, which compose th a; same is of critical int-1 I I I portance to the present invention. The external surface f of the portion; 12;ftom the. channel; 13 on forward fisf I denoted by the; numerfalj :16; 3 This surface is round in I i transverse cross section on any such section along its;

' entire; length, fThejfore. and an contour; of the: surface I I I preferably nearthe'transversewertical plane of the reef end; of the. surface; 16. The longitudinal curve is, very gradual; as shown, and preferably; although not 'neces I 1 I f eer ly; comprises le s than ten degrees or the ifi l 1 33i r I i The'sheil (i is externally threaded as; at 17 Eat a place I to the rear; of the contractible portion :12. The rear; end.

' I portion18of the adjustment sleeve 7 ijsiinternaliy'thread j I f ti v'e shot; pattcrn control device for. carryingfout the aforei mentioned gobjectiv .modifications may; be made in the structure ajsgdisclosed;

i ment of the former.- The sleeve 7 may be provided'wit l 1 I 1 1111 P tia k ur dsurf -ace 29tojfacilrtat 1fts manual m-f tfion.

: i i The ifcir wafrd portion of I sleeve IT forms a wag n I l .means; and 'sjdesignatedj by the: number ZZandi the; front I f I Een'd thereof is: reduced as at 23 and threaded for attachment of the aforementioned compensator 8.; Theintefrior I I surface; 24., of the sleeve portion 2:2 is contoured to mate- I with the surfaceiltiiof'the shell 6. 1 The; surface is accordiingly. concave being round 1 in; cross section. {throughoutits length and longitudinally curviug I inward, on are 1 I I j having the same center} as that of; the longitudinal are I I i j described by thefimmediateiyadjaeentsurface 16. it is I f j desirablei that the sleeve '7' and its intejri'or surface 24. I j extend .forw ar; ly a slight distance? beyond the 'shellf 6 i when the ch'okeisi in'opeh position as s'hown in Fig 2.=

The operation of the device will now be clearly understood. When the sleeve 7 is in its forward position (Fig. 2) the internal diameter of the shell or choke tube 6 is constant throughout its length, a diameter equal to the bore of barrel 5. The choke is then in open condition and each segment has complete exterior backing throughout its length by the sleeve portion 22.

To bring the device to a full choke the sleeve 7 is rotated to move inwardly on threads 17 and the portion 22 becomes a wedge with surface 24 exerting radial pressure upon the surface 16. Segments 15 will yield inwardly to bring the shell portion 12 to the contracted condition shown in Fig. 3. The pitch of threads 17 and 19 is preferably coordinated with the-shell contour whereby the segments are brought to a full choke position upon one complete revolution of the adjustment sleeve. Obviously the choke opening may be varied by adjusting the sleeve less than one revolution as desired. An indicator scale may be provided on the collarltl or sleeve portion 18 to aid in proper adjustment.

In adjusting the choke, surface 2,4 will slide flush along the surface 16 giving complete backing atall positions. Segments 15 resiliently yield primarily at their reduced wall portion 13. When the segments are placed under inward pressure the extended ends of the segments will obviously be moved inwardly. a greater distance than will the rearward or attached portionsthereof) Thus the shot blasts. 1 This, ream-re obviously renders the choke 5 backing of the. fingers is lacking,- the-ref .is a smallerarea I 5 of engagement between. the choke tube and the wedzg'ing I I 3 1 Accordingly there I 3 f greater longitudinally inward pitch of the surface 16 near its extended end is completely compensated for by 1 the like pitch of the forward end area of surface 24.

My invention has two primary advantages which .will

be readily understood. First withthe segments or fingers having uniform and complete backing throughout their length whether in open, full choke, or any position therebetween, they will not become deformedunder repeated surface 5 of the adjustment sleevel mustbe considerable pressure exerted. at these small I I 1 areas of contact; I This makes rotation of the adjustment :I I I 16 onany diametricalbr longitudinal section of} the choke j i sleeve more difficult than in the: present construction. I Q Portion 12 i moves on an are which: curves inwardly In .rny improved: device the :wedging pressure I is exerted I in its forwardprogfression; This are has its center located I i I Both; of these advantages are direct result. of the: 5 I exterior longitudinal: contour of the; forward slotted ;po'r- I I I I tion .of thej shell and the; mating: interior contourofthe 5 20,

haveaccordinglygprovided an; economical and efEecZ- adjustment sleeve.-

lt is under t od that, suitable provided such modifications icotne within the :spirit and j y f 1 scope of} the appended claims; Having nolwl therefore; I a j I I fully illustrated and described my inventionwliat Iclairnf I to be new and; desire to protect: by Letters Patent is: r 5 I I I i 11; .Infa; shot pattern control device for a shotgun-, a 1 j i generally: tubular: shell {for mounting on the} fotwardiend I I j of the gunjbarrel and in axialaligriment therewith; said I j I-Sl1ell having a plurality of; annularly spaced slits in; the; I i wall thereof extending; longitudinally rearwardlv from its front end so as to: divide-the-wallinto a series of forilwardlyg extending fingers'radially contract'able grinder pe-. ripheral pressure to constrict the passage 5 through; the f forward end portion of the shell; a sleeve; encircling the I shell% and secured thereon itor; longitudinal adi sim I I with respect thereto, said sleeve-having ianfannular n 1' i surface in peripheral pressure contact with the; outer j i surfaces of said fingers and throughout substantially the entire lengths thereof, the outer surface of each finger and the inner surface of the sleeve in contact therewith being contoured in a longitudinal direction to follow the curves of concentric arcs, whereby when the sleeve is longitudinally adjusted on the shell the said inner surfaces thereof will continue to maintain contact with the outer surfaces of the fingers throughout substantially the entire lengths of the latter. I

2. A device as described in claim 1 in which the rear ends of the fingers are integrally united with the rear part of the shell by reduced neck portions adapted to bend when the fingers are contracted under the pres sure applied by the sleeve. I

3. In a shot pattern control device for a shotgun, a generally tubular shell adapted to be mounted on the muzzle end of the shotgun barrel and in axial alignment therewith, said shell having an externally threaded rear portion and a choke portion forward of the threaded portion, an adjustment sleeve encircling the shell and having internalthreads cooperating with the rear portion of the shell for longitudinaladjunstment of the sleeve on the shell, the wall of the choke portion of the shell having ;a plurality of slots extending longitudinally rearward from the forward end thereof to divide said portion into a plurality of annually arranged forwardly extending segments adapted to have their forward ends moved radially .inwardly to constrict the passage through the choke portion, said choke portion having an external surface which is circular in cross section atlanypoint throughout its entire length, the outer surfaceof each of said sections andthe inner surface of the sleeve immediately adjacent thereto being longitudinally curved in concentric arcs.

(References on following page) boith accurate and inexpensive to i operate over extended; I I l I .pe riods.ofuse r Second primar feature of any impr h k @5114 I structi'onlie's in the ease and. speed with which it m y b5 i I I i manually adjusted. .In conventionai chokes iwlzlere f i I I 5 unili'or'rnj'ly' over the entireouterisjurface of the fingerpot I tion or. the choke allowing the choke @device. to} be ;ad 5 I Q justed with relative ease. i i i 5 References Cited in the file of this patent 1,892,522 2,153,246 V UNITED STATES PATENTS 2,490,829 1,348,750 Schuster Aug. 3, 1920 2,629,958 1,508,605 Legett et a1 Sept. 16, 1924 5 2,676,429

6 White Dec. 27, 1932 Gibson Apr. 4, 1939 N011 Dec. 13, 1949 Roper et a1. Mar. 3, 1953 Gotterson Apr. 27, 1954

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