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Publication numberUS1131319 A
Publication typeGrant
Publication dateMar 9, 1915
Filing dateJun 30, 1913
Priority dateJun 30, 1913
Publication numberUS 1131319 A, US 1131319A, US-A-1131319, US1131319 A, US1131319A
InventorsJohn Blish
Original AssigneeJohn Blish
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Breech-closure for firearms.
US 1131319 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

J. BLISH.

BRBBGH GLOSURB FOB PIREARMS.

APPLIOATION FILED JUNI'. 30, 1913.

1,131,319. Patented Mar.9,1915.

2 SHEETS-SHEET 1.

J. BLISH.

BRLBGH cLosURB POB. FIREARMS.

APPLICATION FILED JUNE 30, 1913.

Patented Mar. 9, 1915.

2 SHEETS-SHEET 2.

l magP/.9.'

BREECH-CIJOSRE FOR FIREARMS.

Speccation of Letters Patent.

Patented Mar'. 9, 1915..

Application inea June 3c, 1913. seal no. 776,586. Y

T0 all whom it may concern Be it known that I, JOHN BLIsH, commander in the United States Navy, retired, and a citizen of the United States, and resident of Brookline, in the county of Norfolk and State of Massachusetts, have invented new and useful Improvements in Breech- Closures for Firearms, of which the following is a specification.

My invention consists in a new and improved explosion chamber closure, exemplified by a breech closure for firearms, and is adaptable to breech-loading arms of all calibers, which may employ any variety of breech-loading ammunition.

The chief characteristic of my invention is exemplified by the employment of pressure generated by the .discharge of the breech-loading piece, as the sole factor for locking the breech closer, for actuating the breech closer pto open, the breech, and for ejecting the cartridge case, obturator, or other ammunition adjunct remaining in the piece after firing; and also, if desired, for reloading and rering the piece, in case the firearm is of the automatic class. over, according to mv invention, the pressure generated by discharge operates ldirectly and without requiring intermediate mechanical translators of force and motion, in the chief and elementaryv functions of locking the breech closer and opening the same at the proper predetermined time. Ejection of the cartridge case accompanies the opening movement of the breech closer, y

since the cartridge vcase or its analogue is the means through which the pressure generated by discharge of the explosive is communi- .cated to the breech closer. The addition of mechanical adjuncts which confer automatism in reloading the piece is ancillary or supplementary to the main elements of my invention. Y

Heretofore, sov far as I am aware, automatic breech closers have operated through the agency of friction, inertia of parts, or resistance of springs, or several of these factors which have been relied on to control the opening of* the breech closure; or have been operated/'by gas pressure working through mechanical trains. In my invention no resort is had to any of these agencies, as will herein appear.

invention is illustrated in the drawings hereto annexed, in which- Figure l shows in longitudinal elevation Moreand section a model, explanatory of the principlesof my invention; Fig. 2 shows in elevation and section a simple form of breech closer; Fig. 3 shows in section an alternative form of breech closure; Fig. 4 shows another alternative form; Fig. 5 shows a curve of pressures generated in a firearm; and Fig. 6 shows a curve of pressures on a scale different from that of Fig. 5.

In order to explain the conditions under which my invention operates, and which are fundamental to its principle of operation, I refer to Figs. 5 and 6. Fig. 5 is a reproduction of the curve shown in a diagram printed in the Encyclopedia Americana, and shows graphically the firing pressure recorded during an authoritative test of a United States Army eight inch rile. The ordinates represent pressures, the abscissae times, in thousandths of a second. About thirteen thousandths of a second after initial ignition of the charge, the projectile left the muzzle of the riiie. The dotted ordinate line is drawn at this point, X, in Figs. 5 and 6. For purposes of definition, I will term the pressure represented by the curve from zero, or origin, to the dotted ordinate line, the ballistic pressure, and the pressure represented by the remainder of the curve, to the right of the dotted line, as the vanishing pressure. It will be observed that the maximum ballistic pressure is very quickly generated, the ascending curve A (Fig. 5) arriving at the maximum of 61000 pounds in about four thousandths of a second. The expansion, or descending curve which defines the course of ballistic pressure (area B6) arrives at about 12,000 pounds to the square inch when the projectile leaves the piege, and thereafter the curve of vanishing pressure (area (F) descends, reaching zero approximately in 80 thousands'of a second after the initial iring. It will be noted that the velocity of free recoil, represented by curve D, (Fig. 5) does not reach its maxi mum and substantially constant value, until after the projectile haspleft the gun and ceased to be a factor. In Fig. 6 the curve of vanishing pressure is drawn to a scale in which the pressure ordinates are ten times 1Min as large as in Fig. 5. This diagram will be l referred to again.

I now refer to Fig. 1 which shows a model' of the barrel B. Parallel abutment bars B2 are firmly bolted to the receiver B in such manner that their front surfaces, which form guides or Ways on which the breech closer W slides, or is fixed, as thecase may be, are oblique to the vaxis of the-barrel B,

landtherefore to the direction of rearward 'thrust generated within the barrel. p

breech block, or breech closer W is, genin the receiver B, and may be made to bear on the lowerA and upper parts, respectively, of the breech closer l/V. A powerful spring K is inserted in the breech chamber of the barrel B, and a stiff rod B3, carried on a screw threaded head C5 (for which the bore of the barrel B -isV threaded at the muzzle) bears against the spring K.

To demonstrate the principle on which` my breech closure operates, raise the breech closer W and setit against the disk C by.

means of the screw K. Then advance the screw head C5 into the barrel B, until the spring K is compressed to the utmost. T hen retract the screw K. Under the heavy pressure exerted upon it, the breech closer lV is rigidly immovable. It may be moved downward byvexerting great force on it by means of screw K3, but the pressurel of screw K3 must be continued in order to produce continued downward movement ofthe breech closer WV. While the spring pressure is at high value, the breech closer W is held, as in a clamp, of which the. bars B2 on one side and the disk C on the other, constitute the opposed jaws. When the critical point is reached in progressive diminution of the spring pressure, the clamp, or vise-charac- -teristic of'these two opposed members, B2

and C, vanishes entirely and ceases to function; the disk C then acts as a pusher to retire the breech closer W, which slides freely and easily on the bars B2 and disk C. The

point of demarcation between these two successive characteristicsA of the members B2 and C appears to be a very sharp one, at all events, no progressive or gradual disappearance of the rigid clamping function is discernible. Instead of forcing the breech closer downward by means of screw K3, slowly unscrew the muzzle screw C'thus relaxing spring K gradually. When the pressure exerted on the breech closer WV has descended'to a low value, the breech closer W suddenly responds to this residual spring pressure, and slides downward along the ways S on Ythe..abutment barsv B2, Aopening the breech and allowing the disk C (repre sentinga cartridge case) to be ejected from the breechv chamber, and to fly out over the upper surface w and .between the abutment bars B2. Repeated trials of'this demonstration will show that the release of the breech closer W always occurs at almost exactly the same pressure value. According to the laws of friction, if the angle of support, relatively to direction of pressure thrust, be

suchwthat sliding movement between thetwo.

engaging members will result at Vany Ap ressure, it should result at all pressures. Since the demonstrated behavior of the model illustrated in Fig. 1 is contrary to this law, friction is ruled out of the case, being a factor of no substantial consequence. lt is obvious also that the inertiak of the breech closer W plays no part in the operationv of the closure device, and that the only agent relied on to lock the breech closer is the pressure developed in the firearm, acting to cause locking or clamping engagement be-` tween the breech closer and its abutment until the pressure falls to such a value that the laws of friction supervene, when the breech closer slides on its abutment and opens the'breech. y

Fig. 2 illustrates the application to firearm practice of the principles demonstrated by the model shown in Fig. 1. Here the breech closer l/V is provided with a pin wz and a relatively light holding spring fw', of which the function is simply to lift the breech closer W into place and hold it against the cartridge case C preparatory to fir Suitable mechanism. None is here shown,

since I desire to ,disclose and describe my invention in the simplest possible terms, without importing descriptions of auxiliary contrivances which any skilled maker of firearms may supply. With the piece charged and the breech closer in position as shown in F ig. 2, when the piece is fired, the pressures in the barrel develop in tne manner illustrated Iin Figs. 5 and 6. l/Vhile the pressures are high, namely, ,during the entire duration of ballistic pressure and part of'the succeeding vanishing pressure, the breech closer lV is locked fast to the abutment bars B2. When the critical pressure, which vcorresponds to the supervention of the laws of friction over the related parts `W and B2, is reached, the breechcloser W'4 is abruptly moved outward and downward and the cartridge case ejected between the abutment bars B2. Here, as in the case of the model apparatus shown in Fig. l, vthe cartridge case C and bars B2, during the period of ballistic pressure, and up to the instant when Ithe critical pressure of release is arrived atduring the decline of vanishing pressure, act as the two opposed jaws or members of a clamp, holding the breech closer W immovably between them. And when the critical pressure of release is reached, these members B2 and C undergo a sudden functional transformation, cease to act as a clamp, and operate to slide the breech closer open.

Referring to Fig. 6: If the inclination, or Obliquity of the guiding surfaces S, to the axis of the barrel, B is so determined that the critical pressure shall be 500 pounds to the square inch, the point of breech opening is indicated at Y (Fig. 6) and the effect of release due to breech opening and ejection of the cartridge case is indicated by the curve-area E. Relatively speaking, a long time elapses between the departure of the projectile from the barrel and the breech opening. rThe construction of the breech closure may be determined so that at any stage in the vanishing pressure period the breech closer will be released. Preferably, of course, the point of critical pressure will be so determined that enough energy will be available to perform all the operations of breech opening, cartridge case ejection, re-

loading, etc., which may be involved in the complete cycle of the firearm. The main point to be emphasized is, that until the critical pressure is reached in the descent of pressure value, the breech closer is firmly clamped to its abutment, and that when this critical pressure is reached, the breech closer is perfectly free to move on its abutment. Some features of operation which are derivative from this main point deserve mention. No movement of the breech closer over its abutment guides takes place until the pressure of contact is reduced to a low value; therefore, abrasion and wear of the engaging surfaces is avoided, and the breech opening movement, though abrupt, is not unduly violent. No mechanical extractor is required, the cartridge case blowing out of the breech under the vanishing pressure. The ejection of the cartridge case occurs at the earliest possible instant, so that the heat momentarily stored in the cartridge case is in large part radiated after the case leaves the breech chamber, and not into the metal surrounding the chamber. The locking of the breech closure is positive, without requiring any bolt or latch; the opening of the breech closure is free and unrestrained, and not retarded or complicated by any 35 bolt or latch.'n

To illustrate alternative modes of carrying into e'ect the same principle of operation as above explained in connection with Figs. l and 2, I refer to Figs. 3 and 4. ln these figures, the abutment is formed as part of the receiver B', and the supporting and guiding surfaces are cylindrical. In Fig. 3 the cylindrical surface S has its axis at the rear of the breech closer `W, and at one side of the axis of the barrel B, while in IFig. 4, the cylindrical surface S has its axis forward of the breech closer WV, and likewise at one side of the axis of the barrel. In both forms, the abutment B4 or B5 is bored, at b4 or b5, to aHord passage for the ejected cartridge case. The breech closer W is formed with a cylindrical surface in both these instances, which conform to the abutment surface S, and will be provided with suitable means (not shown) for guiding it in its movement over the abutment surface. Whatever the variation in form p or detail of breech closure, the characteristic of my invention resides in an arrangement of a closer and an abutment presenting a surface at an angle of Obliquity or inclination to the direction of pressure thrust (e. g. axis of the barrel) such that, at low values of pressure thrust the closer will slide on the abutment, whereas at higher values, (over and above a critical pressure which is the maximum under which the closer will slide) the closer is rigidly locked or clamped between the abutment and the medium through which pressure is exerted on the closer,.such as a cartridge case, by the pressure alone. The angle at which the' abutment surfaces are inclined to the direction of pressure which in a firearm coincides substantially with the axis of the barrel should therefore be suliiciently great, .e. should approach nearly enough to ninety degrees, to insure the locking or clamping by discharge pressure during the ballistic stage, and yet not so near to ninety degrees as to prevent sliding movement un. der the normal frictional conditions at some value in the vanishing pressure stage. Should the inclination of the abutment surfaces to the axis of the barrel be decreased, the value in the vanishing pressure stage at which the breech closer will unlock, will rise higher, and an angle will finally be reached at which the locking or clamping effect will no longer be obtained. 0n the other hand, should the inclination of the abutment surfaces to the axis of the barrel be increased, approaching a right angle, the value in 'the vanishing pressure stage at which the breech closer unlocks will be diminished, and an angle will finally be reached at which the unlocking effect will no longer be obtained. The practical angle to be selected will lie between these two theoretical limits.

I have ascertained by experiment that with a United States Army service rifle, a proper angle for the slideway formed by plane-surfaced abutment bars, such as shown in Fig. 2, is about 71 to the axis of the barrel. The characteristic action of th'e breech closure herein described lies in clamping the breech closer immovably against the inclined slideway by pressure alone during the relatively high pressure exerted on the breech closer by the Icartridge case throughout the ballistic stage, and for as long there` that the breech closer must begin its sliding movement atthe initiation of pressure-in the firearm, but the demonstration by means of the model shown in Fig. l dispels this impression. The assumption of full pressure is instantaneous, so that there is practically no point in the line of rising pressure which corresponds to the critical point ofbreech closure release in the line of vanishing pressure, which is gradual. Furthermore, it is quite obvious that if the breech closer were to begin sliding on the abutment slideway when under the extremely high pressure of the ballistic stage of discharge, the engaged surfaces of the closer and slideway would suffer yabrasion and Wear. In fact, even though these engaged surfaces be not hardened, they show no sign of wear after many rounds have been yfired in the piece. If any sliding movement of the breech closer were to take place under high pressures, the softer metal of which the cartridge case is composed would inevitably be abraded and portions of it would cling to the harder metal of which the breech closer is composed. `No trace of such action appears This, again, proves conclusively that no sliding begins until the pressure between the engaged surfaces has fallen to a low value. Again, since with the breech closure above described the breech closer opens always at substantially the same predetermined low pressure value, it is quite immaterial to the operation of the breech closure, Whether a full service charge, an excessive charge, a reduced charge, or a blank cartridge. be used; a circumstance .which serves practically to distinguish the above described breech closure system from 'the heretofore known types.

The rbreech closer of a firearm is in its essence a valve, the function of which, as with all valves, is tb control an opening in a chamber, or channel, within which pressure isdeveloped. The principle of my invention, herein explained, is therefore applicable to valves in divers situations, Wherever ,and the like, I employ them illustratively and not by Way of limitation.

I claim: l.l A breech closure system for firearms,

vcharacterized by a mechanically unobstructed abutment slideway inclined to the axis of the firearmbarrel and a breech closure on said slideway; the breech closer and slideway adapted to be immovably clamped together by relatively high discharge pressures exerted onthe breech closer, and relieved from said clamped condition by reduction of discharge pressure to allow the breech closer to slide on the slideway under discharge pressures of relatively low value.

2. A breech closure system for firearms,

characterized by a mechanically unobstructed abutment slideway fixed with relation to and inclined to the .axis of the firearm barrel and a breech closer on said slideway; the breech closer and slideway adapted to be immovably clamped together by relatively high discharge pressures exerted on the breech` closer, and relieved from said clamped condition by reduction of discharge pressure to allow the breech closer to slide on the slideway under discharge pressures of' relatively low value.

3. In a firearm, the combination of a breech closer having a rearward surface inclined to the axis of the barrell and a fori ward surface normal to the axis of the barrel, an abutment having an inclined surface against which the rearward surface of the breech closer rests, said abutment adapted in coperation with the cartridge' case or its analogue, to clamp the breech closer immovably under higher values ofj discharge pressure, and to relax said clamping effect under v a lowervalue of discharge pressure.

4. In a firearm, the combination'of aslideway inclined to the axis of the barrel and a breech closer between the slideway and the cartridge chamber, adapted ,toy be clamped immovably between the slideyvay and. a car- .tridge case by discharge pressure alone. un-

way fixed with relation to the barrel and. inclined to the axis of the barrel and a breech closer between the slideway and the cartridge'chainber, adapted to be clamped im- .movably between the slideway and a cartridge case' by discharge pressure alone, un-

' Avder higher values of the same, and to slide freely in the'slideway under impulse from the cartridge casein response to lower values ishing pressure.

7.1n a firearm, the combination of a breech closure having a rearward surface inclined to the axis of the barrel and a forward surface normal tov the axis of the barrel, an abutment fixed with relation te the barrel* and having an inclined surface against which the rearward surface of the breech closure'rests, said abutment adapted in coperation with the cartridge case or its analogue, to clamp the breech closure iininovably under higher values ofdischarge pressure, and to relax said clamping effect and thereby move the breech closure under a lower value of discharge pressure.

Signed by me at Boston, Massachusetts, this 23d day of June, 191

JOHN BLSH.

Witnesses: k

J OSEPHINE H. RYAN, FLORENCE A. COLLINS.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US7562614May 17, 2006Jul 21, 2009Sa Ordinance, LlcClosed bolt system with trigger assembly for converting a fully automatic submachine gun into a semi-automatic carbine
US7779741Nov 29, 2007Aug 24, 2010SA Ordnance LLCSemi-automatic firing closed bolt-type carbine anti-jamming cartridge loading system
Classifications
U.S. Classification89/17
Cooperative ClassificationF41A3/74