US2611204A

US2611204A - Receiver and action assembly for firearms

Info

Publication number: US2611204A
Application number: US788530A
Authority: US
Inventors: Jr Thomas R Robinson
Original assignee: Marlin Firearms Co
Current assignee: Marlin Firearms Co
Priority date: 1947-11-28
Filing date: 1947-11-28
Publication date: 1952-09-23
Anticipated expiration: 1969-09-23

Description

Sept. 3, 1952 vT. RQ ROBINSON, JR 4 RECEIVER AND ACTION- ASSEMBLY FOR FIREARMS Filed NOV. 28, i947 Patented Sept. 23, 1952 f .anon rvrnhnnisorron assmviatrron:

, FIREARMS Thomaslt; Robinson, 512, Newton, (Donn, assignor to The'Marlin Firearms, Company, New Haven;

001111., a corporation of Connecticut Application November 28, 1947, Serial No. 788,530

Y 12 Claims. 1 1

The present invention relates in general to firearms and more especially to therecelver, breechboltand trigger plate assembly offan automatic self-loading" firearm.

An; objectvof the rinvention'is to provide an improved. receiver-and breechsbolt assembly for insuringztreliable and .iuniformi operation' of a firearm;.

,A'furtherrobjectiof the invention :is to provide improved. breech-bolt .guideemeans in the receiver of.ia.firearm.;whereby the reliable and uniform operation 02 theebreech-obolt :is assured, irrespectiveiofithe accumulation ofiadventitious material within the'receiver; x

A still furtherzobiect of the: invention'is to pro- ,Vider the: receiver? of 1 a1 firearm with improved breechebolt guide meanssfor: reducing frictional drag; between? the: breech-bolt and the interior wall of thesreceiver. andifor insuring auniform cycle-of operations;

A" still: further objectofthe invention is to provide the. receiver of a1 firearm withimproved breech-bolt guide-vmeansswhich is of simple and economicalconstruction an'dwhichis adapted to provide means for attaching atrigger-plate to the-underside of the receiver;

With the'above and other object in'view, as-will appear-to those-skilled in the art from the present disclosure, this inventionincludes all features in the said disclosurewhich are novel over the prior art and which are notclaimed insany separate application- In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig, 1 is-a=sidee1evation of the receiver of an automatic: self-loading firearm including a trigger-platetmountedon the underside thereof and a fragmentary portion-0f the barrel;

Eigez lissasidewelevationin section of the receiver of 1, on. a. vertical plane through the longitudinal axis thereof:

Fig; 3'is anendelevation. in section on. line .3-3 offFig': 1;,

Fig; 4- isaperspectiVevie'w ofltheireceiver of,

the-=flrearm'shown' in Fig. 1; and

Fig. 5 is aperspective view of the trigger-plate which is secured to the underside of the receiver, as: shownin Fig: l.

' Referring to the drawingswhich, for the pur- 2 2,454,885, and Ser. No. 786,232, filed November 15, 1947, patented December 28, l949', a,s;Patent No. 2,492,814, andcomprising, in the main, areceiverindicated generally at [5, abarrel it f xedly secured to the forward: end thereof and areceiver-elementsuchas, forexample; a triggerplate ll attached to the underside ofthe receiver.

The latter comprises a substantiallyscylindrical member preferably formed from a suitable length of tubular steel stock (see Fig: 4), the'rear end of which is closed by'a'receiver-plug 18. The barrel It is adapted to be secured in the forward restricted end ofthe receiver, therestriction of which is provided, for example, by. azrelativelythick-walled bushing I9 welded .or otherwise secured therein so as to divideth'e interior 'of'the receiver into a forward chamber 200i reduced diameter and a concentric axially-aligned rearward chamber 2|. The latter ischereinafter referred to as the breech-bolt guide-chamber, the inside diameter of which; corresponds substantially to theinside diameter of the receiver-tube. Although a receiver" comprising a tubular-member having a cylindrical bushing inserted in one end thereof to form a composite breech-bolt chamber of two diameters is a highly satisfactory. and economical construction, it'will be appreciated that it is within'the purview of-the invention .to form the receiver, including the forward 1 and rearward chambers 28 and El respectively, from a single piece of stock in any well known andapproved manner.

Formed in the underside or bottom. of the breech-bolt guide-chamber 2| of the receiverare a plurality of apertures, indicated-generally at '22, which communicate with thetrigger-plate IT in which the fire-control mechanism (not shown) is adapted to be mounted. A suitable ejectionport 23 is provided intheright-hand side ofthe receiver and comprises a substantially-longitudinal slot communicating with ..the,forwardiohamr ber 20 of the receiver.

Mounted toreciprocate longitudinally inn-the composite breech-bolt chamber of thereceiver, is a'breech-bolt, indicated generally at 24; which as shown in-Figs. l and 2 comprisesla substantially-cylindrical rear end-portion 25 'adaptedto be slidably supported: in" the breech-bolt guidechamber 2! of the. receiver by suitable guidemeans, as hereinafter described; .anda substantially-cylindrical front end-portion 26 of reduced diameter adapted to make'a smooth sliding; fit in the forward chamberZU of the receiver. The breech-bolt may be formed .from two .separate cylindrical elements of different external diameters, the element of smaller external diameter being secured by a welded joint or similar fastening-means in the forward end of the element of larger diameter and in axial alignment therewith. Although a two-piece bolt is quite successful both from the standpoint of operation and economy of manufacture, it will be appreciated that the breech-bolt may be turned out of a single piece of stock. The breech-bolt is adapted to be operated manually by means of a handle 21 which is detachably secured thereto and projects through the ejection-port 23 of the receiver, the handle being cooperatively associated therewith to prevent rotation of the bolt in the chamber, as more fully described in the applications above identifled. Other details of the breech-bolt such as, for example, its firing-pin (not shown), as well as details of the action mechanism, including the firing-plunger and sear, are the subject-matter of the aforementioned applications and, hence, the present description is not burdened with a description of these elements.

Referring particularly to Figs. 2 and 3, the

' breech-bolt and more especially the enlarged rear end-portion 25 thereof is adapted to be supported and guided in the breech-bolt guidechamber 2! of the receiver by improved guidemeans comprising ribs 28 which extend longitudinally of the breech-bolt guide-chamber and are spaced circumferentially around the inner wall thereof. In this connection, it will be noted more especially from Fig. 3 that the diameter of the enlarged rear end-portion 25 of the breech-bolt is appreciably less than the inside diameter of the breech-bolt guide-chamber 2|, as a consequence of which the guide-ribs 28 constitute the sole supporting-means for the rear end-portion of the breech-bolt. In the particular embodiment of the invention illustrated in the drawings, three such guide-ribs are shown, one rib being at the top of the chamber in a vertical plane through the longitudinal axis thereof while the two remaining guide-ribs are formed on opposite sides respectively of the chamber and at angles of substantially 120 with respect to the top guide-rib and to each other. Each guide-rib is provided with alongitudinal bearing surface 29 which is elevated above the circumferential plane of the inner wall of the guide-chamber and which comprises a concave substantially-cylindrical surface of revolution, the radius of which corresponds substantially to the radius of the enlarged rear end-portion 25 of the breech-bolt. In the embodiment of the invention shown herein, the total area of the bearing surfaces 29 of the guideribs is as little as twelve-and-one-half per cent of the circumferential area of the breech-bolt guide-chamber, as a consequence of which the breech-bolt reciprocates longitudinally in the chamber with a minimum frictional drag. Moreover, since the breech-bolt is supported in spaced relationship to the interior wall. of the breechbolt chamber, any likelihood of the breech-bolt being fouled by the accumulation of adventitious material in the receiver, is effectively obviated. Although the specified ratio of the total area of the bearing surfaces of the guide-ribs to the circumferential area of the chamber has been found highly satisfactory, it will be understood that this ratio is by way of example-only and that it is within the purview of the invention both to increase or decrease the area of the bearing surfaces within limits consistent with the satisfactory operation of the firearm.

The circumferentially spaced guide-ribs 28 of the breech-bolt guide-chamber may comprise narrow substantially-solid bars or strips of metal spot welded or otherwise secured on the inner wall of the chamber, but as shown especially well in Fig. 3, it is preferred, from the standpoint of economy, to formthe ribs by a striking-in operation performed upon the exterior wall of the receiver longitudinally thereof and at circumferentially-spaced points on its perimeter. In this manner, the guide-ribs 28 are formed as integral in-struck portions of the receiver, the bearing surfaces 29 of which may be formed, for example, by passing a reamer or similar tool lightly along the inner convex edges thereof to form concave cylindrical surfaces of revolution. Simultaneously, the exterior wall of the receiver opposite the longitudinal in-struck guide-ribs is formed with longitudinal grooves 30. As shown especially well in Fig. 2, the forward ends of the guide-ribs 23 constitute abutments against which the rear end of the bushing I9 is seated in assembling the latter in the receiver.

The longitudinal exterior grooves 30 in opposite sides respectively of the receiver constitute means for attaching the trigger-plate I! to the underside thereof. Referring more especially to Fig. 5, the trigger-plate comprises a substantially-U-shaped member having spaced parallelsubstantially-vertical sides 3|, each of which is provided at itsupper edge with an outwardly-turned flange 32, the inner face 33 of which, as shown particularly well in Fig. 3, constitutes a concave substantially-cylindrical surface of revolution adapted to conform to the curvature of the exterior wall of the receiver. Moreover, each flange is provided along its upper edge with an upwardly-projecting in-turned lip 34 which extends longitudinally thereof from the forward end of the trigger-plate rearwardly for substantially twothirds of its length, each lip 34 being adapted to engage in one of the corresponding grooves 30 in the opposite sides of the receiver, the inherent flexibility of the side walls 3| of the trigger-plate serving to hold the lips 34 thereof resiliently in the corresponding grooves of the receiver. To further insure that the trigger-plate is attached to the receiver securely and against longitudinal movement with respect thereto, the concave flange-portions 32 of the trigger-plate may be fastened by spot welds 35 or equivalent fasteningmeans to the adjacent wall of the receiver.

By providing longitudinal circumferentiallyspaced guide-ribs 28 on the inner wall of the breech-bolt chamber, relatively-large circumferential clearance-spaces are maintained between the periphery of the rear end-portion 25 of the breech-bolt and the inner wall of the guidechamber, as a consequence of which the longitudinal reciprocating movement of the breechbolt whether by recoil, spring or hand manipulation will be substantially free irrespective of the inclusion of adventitious material in the breechbolt chamber. It will be evident too that since the guide-means engages the periphery of the breech-bolt only along longitudinal circumferentially-spaced areas thereof, the resulting circumferential clearance-spaces between the periphery of the breech-bolt and the inner wall of'the chamber extend without material obstruction from front to back of the breech-bolt, thus precluding the formation of an air-cushion between the rear end of the breech-bolt and the forward end of the receiver-plug. Moreover, by providing guide-ribs having bearing surfaces of relativelyaeiigeoc small-area; the 1r1ctional-dragbnthebreech-bQlt is reducedtoaminimumvalue; I V

- As-a' consequence of these characteristicfeatures of the invention; the operation of the breech-bolt particularly in automatic self -loading'firearms is-reliableand'uniform. In this connection; it should be pointed out that the adaptationof' the invention to anautomatic firearm is particularly desirable in order to eliminate variations in its-"operationacycle, but that the invention is equally adapted fon use successfully with all firearmshaving;a reciprocable longitudinallysliding breech b'olt;

The invention-may be carried out in otherspecific ways thanthose herein set I forthwithout departingfrom the spirit and essential characteristics of theinvention; and; the present embodiments are; therefore; to be considered in all respects as illustrativeand not restrictive, and all changes coming within the meaning and equivalency range-of the appended claims are intended to be embraced therein.

I claim:

1. In a firearm the combination including: a receiver having a breech-bolt chamber; breechb'olt guide-means on the innerrwall thereof said gu'ideem'ean's comprisin circumferentially spaced parallel ribs extending longitudinally. of said chamber; and a breech-bolt supportedjn said chamber by said ribs in relatively widely-spaced relationship to the inner wall of said chamber for longitudinal reciprocablemovement in said chamber.

2: In a firearm the-combination including: a receiver having a breech-bolt chamber; breechbolt guide-means on the inner Wall thereof said guide-means comprising circumferentially-spaced parallel ribs extending longitudinally of said chamber, and bearing-surfaces extending longitudinally of said ribs, said bearing-surfaces being concentric with respect to the longitudinal axis of said receiver; and a breech-bolt supported in said chamber on said bearing surfaces for longitudinal reciprocable movement in said chamber.

3. In a firearm the combination including: a receiver having a breech-bolt chamber; breechbolt guide-means on the inner wall thereof said guide-means comprising circumferentially-spaced parallel ribs extending longitudinally of said chamber, and bearing-surfaces of substantiallyequal area extending longitudinally of said ribs said bearing-surfaces being concentric With respect to the longitudinal axis of the said receiver and constituting in area substantially as little as twelve-and-a-half per cent of the corresponding inner circumferential area of said chamber; and a breech-bolt supported in said chamber on said bearing-surfaces for longitudinal reciprocable.

movement in said chamber.

4. In a firearm the combination including: a receiver having a breech-bolt chamber; breech-= bolt guide-means on the inner wall thereof said guide-means comprising cireumferentially-spaced parallel ribs consisting of metal struck inwardly from the exterior wall of said chamber and extending longitudinally thereof; and a breech-bolt supported in said chamber on said inwardlystruck ribs in relatively widely-spaced relationship to the inner wall thereof for longitudinal reciprocable movement in said chamber.

5. In a firearm the combination including: a receiver having a breech-bolt chamber; breechbolt guide-means on the inner wall thereof said guide-means comprising circumferentiall -spaced parallel ribs consisting: of-metalstru'ck inwardly fromtheaexterior'wall oiisaid chamber andextending longitudinally: thereof" and bearing-surfaces extending-longitudinally.of said inwardly struck ribs; said. bearing surfacescomprising concentric"cplindricalf sufaces of revolution of substantially-equal area and radius; the radius of each concentric surface being: measured from the longitudinal axis of the receiver; and a breech-bolt supportedin said chamber on the said-bearing surfaces of saidinwardly-struck ribs for-longitudinal reciprocable movement in said chamber.

6; In a firearm-the combination including: a receiver having abreech-bolt chamber; breechbolt guide means on the inner wall ofsaid chamber comprising longitudinal circumferentiallydiscontinuous bearing-surfaces struck inwardly from-the exterior wall of said chamber and arranged to form longitudinal circumferentially spaced grooves inthe exterior wall of said chamber; and-anelement'of the receiver constructed andarrangedto be attached to the exterior Wall of said chamberby cooperative engagement of said element with the said longitudinal'circumferentia-lly-spaced exterior grooves thereof.

'7; Ina firearm'the combination including: a receiver-having a breech-bolt chamber; breechbolt guide-means on the inner-Wall of said chamber comprising longitudinal circumferentiallyspaced ribs struck inwardly from the exterior wall ofsaid chamber and arranged to form longitudinal circumferentially spaced grooves in the ex= teriorwall of said chamber; a'triggerplate; and means to'attach said trigger-plate to said receiver comprising elements of said trigger-plate arranged to engage in the said longitudinal circumferentially-spaced grooves in the exterior wall of;

said chamber.

8. In a firearm the combination including: a receiver having a breech-bolt chamber breechbolt guide-means on the inner wall of said chamber comprising circumferentially-spaced ribs struck inwardly from the exterior wall of said chamber and arranged to form longitudinal circumferentially-spaced grooves in the exterior wall of said chamber; a trigger-plate; means to attach said trigger-plate to said receiver comprising resilient spaced-parallel lips on the upper edges of said trigger-plate arranged to snap into the said longitudinal circumferentially-spaced grooves in the exterior wall of said chamber; and fastening-means to secure said trigger-plate to said receiver against longitudinal movement with respect thereto.

9. In a firearm the combination including: a receiver having a breech-bolt chamber; breechbolt guide-means on the inner wall of said chamber said guide-means comprising circumferentially-spaced ribs struck inwardly from the exterior wall of said chamber and arranged to form longitudinal circumferentially-spaced grooves in the exterior wall of said chamber; a breech-bolt supported on said circumferentially-spaced ribs for longitudinal reciprocable movement in said chamber; and a trigger-plate constructed and arranged to be attached to the exterior wall of said chamber by cooperative engagement with the said longitudinal circumferentially-spaced grooves thereof.

10. In a firearm the combination including: a receiver having a breech-bolt chamber; breechbolt guide-means on the inner wall of said chamher said guide-means comprising circumferentially-spaced ribs struck inwardly from the exterior wall of saidchamber and arranged to form longitudinal circumferentially-spaced grooves in the exterior wall of said chamber; a breech-bolt supported on said circumferentially-spaced ribs for longitudinal reciprocable movement in said chamber; a trigger-plate; and means to attach said trigger-plate to said receiver comprising resilient spaced-parallel lips on the upper edges of said trigger-plate arranged to snap into the said longitudinal circumferentially-spaced grooves in the exterior wall of said chamber.

'11. In a firearm the combination including: a receiver having a breech-bolt chamber; breechbolt guide-means on the inner wall of said chamber said guide-means comprising circumferentially-spaced ribs struck inwardly from the exterior wall of said chamber and arranged to form longitudinal circumferentially-spaced grooves in the exterior wall of said chamber; a breech-bolt supported on said circumferentially-spaced ribs for longitudinal reciprocable movement in said chamber; a trigger-plate; means to attach said trigger-plate to said receiver comprising resilient spaced-parallel lips on the upper edges of said trigger-plate arranged to snap into the said longitudinal circumferentially-spaced grooves in the exterior wall of said chamber; and fasteningmeans to secure said trigger-plate to said receiver against longitudinal movement with respect thereto. I

12. In a firearm the combination including: a receiver; a bushing in the forward end of said receiver, said bushing being arranged to form a forward breech-boltchamber of reduced diameter and the portion of said receiver rearwardly of said bushing constituting; a rearward breechbolt chamber of relatively-large diameter; breech-bolt guide-means on the inner wall of said rearward chamber comprising circumferentiallyspaced parallel ribs extending longitudinally thereof; abutments at theforward ends of said ribs for engagement by the rear end of said bushing; and a breech-bolt adapted to be mounted in said forward and rearward chambers for reciprocable movement therein, said breechbolt having a reduced substantially-cylindrical forward end arranged to be slidably supported on'the inside wall of the forward chamber of said receiver and an enlarged substantially-cylindrical rear end arranged to be slidably supported only by the longitudinally-extending ribs of the rearward chamber of said receiver.

THOMAS R. ROBINS-ON, JR.

REFERENCES CITED.

The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,291,689 Sheppard Jan. 14, 1919 2,049,776 Hyde Aug. 4, 1936 2,403,306 Sampson et al July 2, 1946 2,425,684 Patchett Aug. 12, 1947 2,478,774 Meinel Aug. 9, 1949 2,481,910 DArdenne Sept. 13, 1949 FOREIGN PATENTS Number Country 'Date Great Britain Aug. 12,1946