US1788279A - Bolt-return accelerator - Google Patents

Description

Patented Jan. 6, i931 PATENT oFFIcE RICHARD M. CUTTS, OF WASHINGTON, DISTRICT OF COLUMBIA BOLT-RETURN ACCELERATOR Application filed August 5, 1927. Serial No. 210,950.

This invention relates to automatic fire arms and more particularly to a bolt return accelerator and fire rate controller in connection therewith, having for its object to 5 provide a construction simple in parts and more efiicient in action than those heretofore proposed.

With these andother objects in view the invention consists in the novel details of construct-ion and arrangements of parts as will be more fully hereinafter disclosed and particularly pointed out in the claims.

Referring to the accompanying drawings forming a part of this specification in which like numerals designate like parts in all the views,-

Figure 1 is a longitudinal sectional view of a device made. in accordance with. this invention;

Figure 2 is a longitudinal sectional view of a modified form of the invention;

Figure 3 is a transverse sectional view taken as on the-line 3-3 of Figure 2 and looking .inthe direction of the arrows; and

Figure 4 is a diagrammatic view illustrating a machine gun with a recoil check device as well as the bolt return acceleratorforming the subject matter of this invention.

In order that this invention may be the better understood it is said that in all fire arms, except those of very low power, which use the power of the discharge in recoil for extracting and reloading, the operating parts travel with such forces and velocities as to make it necessary to absorb the power and velocities of these parts in excess of that necessary for operation. This has been here tofore accomplished by various means including recoil mechanisms, springs, and but fers of many types and sorts, designed to absorb the blow imparted by the bolt at the end of its travel without damage to the gun or its parts, and prevent the too rapid return of the bolt with a consequent excessive rate of fire. All of this has been necessary to avoid breakage and crystallization of the various. parts of the gun and its operating mechanism due to the exceedingly severe blow imparted by the said bolt, in fire arms of any power, and to prevent a too great speed of return of the bolt.

The object of this invention is not to provide an improved bufier mechanism per se but, on the other hand, is directed to the pro- 5 vision of a device which while overcoming the striking energy of the rearwardly moving bolt as transmitted through any heretofore known buffer mechanism will store a definitely regulated part of said energy to be used in controllably augmenting the return velocity of said bolt, thus obtaining desired variations in the rate of fire of the gun. Further, by reason of the rate of fire being obtained by bolt return velocity, there will 5 reduce the power of the recoil astransmitted 7 through the operating parts, as a result of which excessiverecoil impacts are no longer necessary. In order to insure positive operation sufficient recoil force must be permitted to pass to these parts to produce successful a and positive functionin of the arts only, the unwanted balance being negatived. Thus it results that with the use in connection with a recoil operated automatic fire arm of a device made in accordance with the disclosures a of the above patents, the bolt strikes at the end of its travel' with a much reduced blow which, however, owing. to the necessity of positive operation is still sufliciently great to necessitate the use of a buffer. Under 9 these circumstances the gun has a strong operating balance, and functions successfully in all its parts, but owing to the reduced power and velocities stored in these operating parts, and as a direct consequence there- 9 of,'the fire rate or number of shots per minute'is reduced below that which is desirable.

The bufl'er mechanism used in connection with the invention about t9 be described may 1 virtue of the inventions covered by be of the conventional design illustrated in the drawings or it may be any one of a number of patented or otherwise known buffers. The invention herein disclosed consists ,of an assembly consisting of a flexible mounting of any standard buffer, and in addition thereto and in connection therewith, a separate and distinct mechanism, mounted in connection with the flexibly mounted buffer, known as a bolt return accelerator and fire rate controller. By means of this invention, a certain definitely adjustable amount of the energy transmitted to the flexibly mounted buffer by the bolt is absorbed and stored in springs beforethe bufier becomes fully "o erative as a buffer, so that after this energy is taken off, the buffer cushions and checks the remaining striking energy of the bolt. The bolt, then having its rearward movement checked, receives the energy previously stored in the springs to overcome its inertia and to start its return action at speed, and moves forward, the regular operating spring continuing the acceleration of said bolt until the same is seated. r

The bolt movement is a reciprocating action and normally its greatest velocity is in recoil or a movement to the rear, and therefore, due to the necessity of absorbing this energy at a rate which will cause no damage to itself or resistant elements, the return of the bolt in a forward movement is comparatively slow. By means of the stored forces in the return bolt accelerator about to be described, the speed at which the bolt is returned is controllable and, with a constant speed in recoil, the variation in the return rate of speed of the bolt causes the fire of the gun to be raised or lowered within certain desirable limits. The speed rate of the bolt return may be fixed by a non-adjustable spring of certain dynamic properties, or raised and lowered at will by the provision of an adjustable member to alter the tension and throw of the spring. It will-readily be seen from the following description and with reference to the drawings that this control is obtained in an exceedingly simple and direct manner.

As the blow of the bolt in recoil, even with the reduced velocity caused by e application of the device covered in the patents hereinbefore mentioned, is quite severe owing to the necessity of maintaining a positive operating balance, the construction of the return bolt accelerator is such that any spring failure in it merely causes the gun to assume the rate of fire that it had before the accelerator was engaged and brought into action, as the buffer in such circumstances and in its rearward position will act as a simple buffer as originally designed. Thus it will be seen that should there be a failure in a spring, the device would still be safe, in that no special damage to the gun or its parts would ensue and the gun would still continue to function.

Due to the construction and assembly of the accelerator, the spring therein can nevertake the full blow of the bolt recoil, nor can it be stressed beyond its designed load, as a result of which it will not ordinarily be subject to crystallization and breakage. This safety feature must, however, be provided to prevent serious consequences resulting from possible faulty material, should it be attempted to take the full bolt blow on a-spring.

In the drawings the return bolt accelerator and fire rate controller is illustrated in two forms, Fig. 1 showing them in tandem arrangement and Fig. 2 showing them in parallel relation." As before stated, this invention is not to be limited to the particular embodiinents of the buffer construction shown, as other arrangements of springs and combinations'of parts are possible, and further any buffer having either springs, discs, liquid or air checks, etc., may be mounted in its entirety under the same basic principle as the conventional buffer shown in the figures of the drawings, all within the scope of this invention. 4

To specifically bring out the'embodiments of this invention reference is made to the accompanying drawings which, however, in addition to this invention illustrate a typical buffer mechanism. As follows, 1 represents a plug adapted to receive a blow from the rear end of the bolt represented by the dotted line 2, said plug being provided on the opposite end with a headed portion 3 adapted to slidingly fit within the casing 4'having an apertured shouldered end 5. The casing 4 contains a plurality of absorbent disks of fiber or leather or in combination, to permit the greater absorption of the'bolt blow possible, and variable in assembly according to the power of the gun used. Each disk may be centrally apertured. to provide the air channel 7 These disks are adapted to contact with the head 3 of the plug 1 and are re tained in position by the plug9 screw threaded into the rearmost portion of the casing 4 in such manner as to permit the withdrawal of the disks from said casing, and to regulate the compression of the pile of disks. It will be understood that other buffers designed to accomplish the same object may be used in this invention in place of the typical buffer above described. The casing 4 of the typical bufl'eris slidingly received in a' guide chamber 11 the forward end of which is screw threaded into a boss formed on theback plate 12 of the machine gun casing, said guide chamber being provided with a suitable oiling mechanism 13 in the u per part thereof and an oil drain 14 in the lower portion thereof.

To prevent a rotation of the casing 4 within the chamber 11, the former is provided with an elongated slot 15 adapted to be engaged by a pin 16 carried by said chamber. Washhaving integrally formed interior ring 26 adapted to take against the.

ers 17 and 18 preferably of fiber and steel respectively are interposed between the forward end of the casing 4 and the shouldered forward end portion of the chamber 11 as will be readily. apparent from the drawings, said washers adapted to permit the plug 1 to slide therethrough.

The rear end of the guide chamber 11 is enlarged to provide a recess 20 to contain a spring 21 under light tension against the enlarged head 22 of the casing 4 said spring adapted to force the casing 4 slightly to the rear. Locking pins 23 and 24 secure the plug 9 in adjusted position with relation to the casing 4, the exterior surface of the head 22 of said casing adapted to slidingly fit the interior surface of the enlarged rear end of the guide chamber 11.

Screw threaded exteriorly of the rear end of the guide chamber 11 is a second casing therewith an extreme rear end of the chamber 11. Fitted adjacent the ring 26 is a pair of washers 27 and 28, the former being of a resistant material and the latter preferably of steel, the purpose of the washers being to receive the full blow of the buffer composed of the disks 6 andthe case 4 when the bolt 2 strikes the plug 1 extending through the back plate 12 of the gun. These washers 27 and 28 have an inner opening of greater diameter than plug 9 to accommodate the adjustability of plug 9 and to prevent this plug when protruding from case 4 from taking the force of the recoil blow, the head 22 of case 4 impacting against these washers before plug 9 could strike 26. A driving plug generally indicated by the numeral 30 is provided with a circular extension 31 adapted to slidingly fit the interior of the casing 25 and provided forwardly of said extension with a cylindrical portion of a length to reach and contact with the plug 9 associated with the proper elements, the washers 27 and 28 being positioned around said cylindrical portion. VVit-hin this cylindrical portion is a hollow sliding plug 32 pressed against the aforesaid plug 9 by a very light compression spring 33 interposed between the plug 32 and the inner extremity of the cylindrical portion of the driving plug 30 all as clearly shown in Fig. 1. The purpose of the spring 33 is to lightly push said driving plug to the'rear. To the other side of the extension 31, the driving plug is provided with an extending portion 34 adapted to receive circumferentially a tension spring 35 the other end of which passes over an extension 36 formed on the forward end of the rate adjusting plug 37 screw threaded interiorly of the casing 25. That is to say, the spring 35 is put under tension by screwing the rate adjusting plug 37 into the chamber 25 by means of any suitable wrench applied to the-squared extension 38 on tht rear portion thereof.

The space within the chamber 25 is mad sufficiently large to receive a heavy duty spring 40 likewise placed under tension by the rate adjusting plug 37, the forward end 01 the 5 ring lying in contact with the extensior 31 o the driving plug 30, said extension being provided with a plurality of small apertures 41 to relieve any air pressure that may accumulate on the forward side thereof. The plugs 9, 32, 30 and 37 may all be suitably provided with a central passage likewise to relieve any air pressure that may accumulate within the structure as a whole, 42 are indentations formed in the exterior surface of the chamber 25 by means of which a suitable wrench may be applied thereto for the purpose of screwing the same securely to the chamber 11.

From the foregoing description of parts it will thus be seen that when a blow from the bolt 2 moving in the direction of the arrow is given to the plug 1, the same is forced in a rearward direction, the immediate shock of said blow being received by the absorbent disks 6 which oppose but little resistance, at this stage of the movement, but impart a rearward motion to the casing 4 by the said force, and in this rearward movement the driving plug 30 will be moved toward the rear against the rapidly increasing tension of the springs 35 and 40, which may be single or double but always suitable in dynamic power to the 'gun on which they are used. The rapidly increas ing tension of springs 35 and 40 (leaccelerate the bolt and case 4, storing this energy for bolt return acceleration. When sufficient energy for the desired degree of return bolt acceleration has been taken off the headed portion 22 of the casing 4 will contact with the washer 28 and move the same against the resistant washer 27 which is firmly held against rearward movement by the internal ring 26 of the casing 25 which is in turn rigidly secured to the back plate 12 of the gun by the intermediately disposed chamber 11, but the parts are so dimensioned as to permit the deaccelerated bufi'er case 4 to come to its seat without damage. Springs 21 and 33 and the plug 32 always insure the parts of the buffer and the accelerator coming to rest between both blows, with all elements setting to the rear with a light pressure and interconnected, thus avoiding separate and distinct velocities among the parts as well as allowing for the variable position of plug 9 when the disks 6 are new or have been compressed from long firing of the gun.

The rearward movement of the driving plug. 30, as stated above, compresses the springs 35 and 40, thus storing part of the energy of the bolt in said spring to a degree determined by their dynamic properties and the position of the rate adjusting plug 37.

[en the buffer portion of this device has versed the distance of the space 43 between end of the casing 4 and the washer 28, the ension 22 of said casing impacts through washers against the internal ring 26 of accelerator casing 25 and thus the buffer is 'ested in its rearward travel. When this :urs only a determined portion of the argy of the bolt has been absorbed by the rings and and no additional energy a be absorbed by them since the bufier cas- 4 has been stopped by said ring 26 or in her words, by the rear plate 12 of the gun which it is rigidly secured. The bolt still- ,ving considerable energy, and the butter sing 4'having been stopped, said energy -ives the plug 1 contacting with the bolt 2 Lckward, further compressing the absorbit disks 6 until the rearward motion of the- )lt is checked. The energy stored in the springs 35 and 40 :ting through the ufler, and through the disks 6 and plug 1 on 1e bolt 2, overcomes the inertia of the bolt,

nd imparts to it a rapid return velocity, to a egree dependent on the amount of energy sored in said springs 35 and 40. This ve- )city is picked up and increased by the contant of the bolt return spring, not illustrated, nthe gun mechanism.

The amount of energy to be absorbed by prings 35 and 40, and in consequence the Me of fire, is adjusted by altering thetension r length of throw of these springs by screwng in and out the plug 37. The direct re- :ult of the energy so applied to the bolt is ;o controllably accelerate its return to the- :losing position, and regulate the rate of fire by this means. The acceleration of the .forward movement of the bolt results in a further improvement in gun action by more nearly equalizing the forces in the reciprocating action of the bolt, or in other words, the return force of the bolt more nearly approaches its rearward force, the approximation of the impact values reducing the v bration of the mount or carriage.

When the accelerator elements 37, 35, 40, 30, 33 and 32 are removed, the spring 21 holds the bufier elements against 26, 27 and 28, and gun operates at a rate of speed set by the resiliency of the disks 6 and the bolt return spring alone, the buffer acting merely as a buiter as it was designed to do. Accident to the accelerator, or accidental loss of oper ating parts does not prevent the firing of the gun. Overcompression of the springs 35 and 40, by accidentally screwing the plug 37 too r'ar in, is avoided by the forward pro ect on 36 of the plug 37 and the rearward projection 34 of the driving plug 30, the lengths of said project-ions being so calculated as to'cause contact therebetween before Overcompression vis reached. By omitting the adjustable feai ture of plug 37, and installing a spring of movement,

driving plug 30 on thethe requisite dynamic variation in the throw, a general rate of fire may be fixed within quite definite limits by a set rate of bolt return acceleration with a back plate blow reduced below that afforded 1 by any particular butter.-

In Fig. 2 is shown a modified mounting of the parts described above with the result that the same actions are obtained, and same numerals have been given to like parts wherever possible. In other words,.in this construction there is provided the plug 1, the casing 4, the disks 6, secured in said casing by the plug 9, and a chamber 11 screw threaded to the rear plate 12 of the gun and adapted to slidingly receive the casing 4 substantially in identical form as were parts of Fig. 1. provided in its forward portion with elongated diametrically disposed slots and 51 adapted to slidingly receive opposed lugs 52 and 53 carried by the casing v4. 11 either side of said lugs are disposed washers 54 and 55 adapted to slidingly fit the exterior of the chamber 11, the purpose of said washers being to receive ends of compression springs 56 and 57 respectively, the former of which is of far greater strength than the latter. The spring 57 is disposed between the washer 54 and the end of a rate adjusting cap 58 adapted to screw exteriorly onto the rear end of the chamber 11, said cap being provided with a squared extension 59 to which a suitable wrench may be applied for the purpose of varying the tension placed upon the spring 57. The springs 56 and 57 as well as the extremities of the lugs 52 and 53 and the forward end portion of the cap 58 all lie the corresponding substantially in the same cylindrical-plane so that a guard member 60 may be slipped thereover and screwed to the external portion of the boss formed on the back plate 12 of the gun. This guard may be provided with any suitable oiling aperture such as 61 in its upper side, and the under portion of the chamber 11 may be provided with a suitable oil drain such as indicated at 62. The rear portion of the chamber 11 is closed by a plug 65 threaded therein adapted to adjacently receive the contacting washers 27 and 28 which are exactly similar in composition and duty to the washers bearing the same numerals described above. The plug 65 may be secured to the chamber 11 in adjusted position as by the locking pin 66, and the chamber 11 may be similarly secured to the rear plate 12 of thegun as by the pin 67.

The action of the modified form of device shown in Figs. 2 and 3 is more or less similar to the action of the device illustrated in Fig. 1 but may be briefly described as follows. When the bolt hits the plug 1, the buffer comprising the disks 6, plug 9 and casing 4 is as a whole moved rearwardly, durin said the lugs 52 and 53 throng the properties with no The chamber 11, however, is p instrumentality of the washer 54 creating a pressure upon the spring 56. The limit of movement of the casing 4 is reached when the head 22 thereof has contacted with the washer 28 and caused the resilient washer 27 associated therewith to be compressed to its limit, the plug 65 serving as a stop for said washer. When this has occurred then the balance of the power from the blow of the bolt is transmitted to the disks 6 which are put under compression and this balance is transmitted from plug 65 connectedly to the back plate of the gun 12.

However, it is to be observed that the spring 56 during this rearward movement of the buffer elements has been placed under compressiom'or in other words, a large portion of the energy of the blow by the bolt has been absorbed by said spring and therefore when the deaccelerated bolt and buffer has come to rest, the spring 56 will impart I to said bolt a forward movement through the instrumentality of the interposed members 54, 52, 4, 6 and 1. The result is that the bolt is given a return acceleration or velocity which is picked up and increased by the constant of the bolt return spring in the gun mechanism (not shown). The light spring 57' is always under tension, to insure all parts of the buffer and accelerator mechanism being settled in contact, with a rearward force when the blow of the bolt is delivered on plug 1, and holding case 4 of the buffer in contact with 65 when for any reason the ac celerator element has been removed or dam aged. The parts of the device shown in the modified form of construction are so dimensioned that by removing the ca 58 access may be had to the plug 65 which may then be readily removed as well as the washers 27and 28 for the withdrawal of the disks 6 contained in casing 4. Access may be had to the plug 9 for adjusting the tension upon 1 the disks 6 without removal of the cap 58 and plug 65 due to the central apertures provided in each as well as those provided in the washers 27 and 28.

As was the case with the device illustrated in Fig. 1, the modified form just described may as well be used in connection with the invention disclosed in my aforementioned patents. That is to say, without the accelerator elements 58, 56, 54,'the springs 57 would hold the buffer elements against 28, 27 and 65 whereupon the gun would operate at a rate of speed set by the resiliency of the disks 6 and the bolt return spring, not illustrated, alone. Any accidents to the accelerator parts, or the accidental loss of the operating parts of the accelerator would not prevent the firing of the gun exactly as was the case as stated before in reference to the tandem construction of this invention. Further overcompression of the springs 56 is avoided byso dimensioning the cap 58 that its rear wall will impact on plug 65, before the spring 56 can be overcompressed. In order to give a clear conception of the forces involved in this field with a certain machine gun the bolt blow drove plug back inch before case 4, seated against washers 27, 28 and stop 26. During this distance the resistance of calibrated spring 40 rose from zero to 860 lbs. This stored energy was returned smoothly to the bolt in accelerating its return, resulting in the desired rate of fire. When the spring efl'ect was increased to; 1,013 lbs. the rate of fire was excessive.

From the foregoing it will thus be seen that by thisinvention it is possible to accelerate the speed or velocity or return of the operating bolt to its closed position. In other words, said bolt has mechanism which normally operates to return the bolt to closed position, but this mechanism does not fully operate upon the bolt to give the same controllable material velocity at the time the bolt is ready to start its return movement. By this device, the springs and store a portion of the energy or force received from the rearwardly moving bolt imparted to said springs through the bufier mechanism, and this stored force is subsequently released or transmitted back through said bufier mechanism to the bolt to give said bolt a positive controllable initial movement which will controlla'bly accelerate its return velocity as a result of which the rate of fire of the gun is increased over that at normal without the use of the springs 35 and 40'. The plug 37 may be adjusted to increase or diminish the tension of the springs 35 and 40, and as the tension is so changed so is the acceleration imparted to the bolt in its return movement.

Therefore it will be seen that this invention provides a means to arrest the rearward movement of the bolt, said means being the buffer mechanism. In combination with this bufi'er mechanism there is provided means influenced by said bufler mechanism to freely and instantaneously accelerate the forward movement of the bolt, said accelerating means being adjustable, compressible and adapted to be placed in tension so that the said acceleration imparted to the bolt is made controllable as well as variable. It will also be seen that the buffer mechanism is adapted to transmit and store a portion of the bolt recoil force in the springs 35 and 40, said portion being sufiicient to accelerate the return velocity of said bolt.

In guns adapted for automatic fire provided with a moving bolt and a buffer mechanism therefor, the rate of fire has been capable heretofore of presetting by an adjustment,

but due to variance in the powder charge used in connection with the projectiles to be fired, this presetting has not been capable of being made constant. With the compensating device disclosed in said Letters Patent No.

" to the barrel, to reduce the int-ial recoil blow.

Owing to hot and cold oil and variations in viscosity and gland leakage, this reduction in recoil is variable and inconstant, and the rate of fire is accordingly variable and inconstant. With the application of the device covered by the patents above referred to these recoil mechanisms are completely removed, and the variation in recoil permitted by them is no longer a factor. It therefore may be prop erly stated that the compensating device will automaticall take care of the constancy of the rate of re as established by uniformity in recoil action.

' However, with the use of such a compensating device as disclosed in said patents, the action of the bolt is considerably slowed and therefore the impact of said bolt upon the buffer mechanism employed will be correspondingly decreased with the consequent slowing of the return of the bolt to its closed position. With the device disclosed in the drawings associated with the buffer mechanism, the speed of return of the bolt under these conditions may be controllably in creased, by placing the springs and 40 under the required tension. Therefore the exceedingl uniform rate of fire from a gun provided with a compensating device (which would normally slow down the action,) is or may be, retained at this rate, or controllably increased by the provision and graduated use of springs 35 and 40 without the usual variable excessive strains and shocks on the gun mechanism. In the action of this improved device the desired acceleration in the velocity of the bolt during its closing movement is imparted; by a force which has been stored in deaccelerating the speed of the bulfer mechanism during itsrearward movement and the energy utilized in such dea/cceleration consesequently stored, is returned (with a consid erable time and distance factor in application) through said bufier mechanism to give which in turn will be transmitted smoothly and positively to the bolt as will be readily apparent from the foregoing. It will be understood that this improved device may be used to obtain an increased rate of fire and better bal ance in the bolt reciprocating forces in automatic guns, whose ower in recoil, due to operating factors, or ow powered ammunition,

is so low as to have a rate of fire below that desirable.

It is obvious that those skilled in the art may vary the details of construction as well as the combination of parts without departing from the s irit of theinvention and therefore it is not esired to be limited to the foregoing except as may be. demanded by the claims.

What is claimed is 1. In a. gun'provided with a reciprocable bolt and adapted for automatic fire the combination of a reciprocable buffer to arrest the rearward movement of the bolt; and means influenced by said buffer to accelerate the forward movement of said bolt.

2. In av gun provided with a reciprocable bolt and adapted for automatic fire the combination of a slidable buffer to arrest the rearward movement of the bolt; and adjustable means influenced by said buffer to controllably accelerate the forward movement of said bolt.

3. In a 11 provided with a reciprocable bolt and a apted for automatic fire the combination of bufier' means to arrest the rearward movement of the bolt; and compressible means coaxial with and influenced by said buffer means to accelerate the forward movement of said bolt.

4. In a gun provided with a reciprocable bolt and adapted for automatic fire the combination of reciprocable buffer means to arrest the rearward movement of the bolt; and

means influenced by said bufier means and acting therethrough to accelerate the forward movement of said bolt.

5. In a 11 provided with a reciprocable bolt and a apted for automatic fire the combination of buffer means to arrest the rearward movement of the bolt' upon impact therebetween; and means coactively infiuenced by and aligned with said buffer means to accelerate the forward movement of said bolt.

6. In a gun adapted for automatic fire and provided with. a reciprocable buffer mechanism, means to vary the rate of fire in accord-- ance with the accelerated return velocity im-' the reciprocating parts through the force of.

the excess energy unabsorbed by said mecha-- nism from recoil.

7 In a gun adapted for automatic fire and provided with a reciprocating bolt and slidable buflt'er mechanism therefor, means coaxial with said bufier mechanism to store a portion of the bolt recoil force sufficient to accelerate the return velocity of said. bolt and to transmit said stored force directly to said bolt through said buflz'er mechanism, whereby the rate of fire of said gun may be increased.

8. In a gunadapted for automatic fire and provided with a reci rocating bolt and buffer mechanism there or, means to receive ment of said buffer i and provided with and store a portion of the bolt recoil force received by said mechanism through its axial displacement said force sufiicient to accelerate the return velocity of said bolt" and to transmit said stored force directly to said bolt back through said bufl er mechanism, whereby the rate of fire of said gun may be increased.

9. In a gun adapted for automatic fire and provided with a reciprocating bolt and buffer mechanism therefor, adjustable means to receive and store through the axial displacemechanism a variable portion of the bolt recoil force sufiicient to accelerate the return velocity of said bolt and to transmit said stored force directly to said bolt through said bufier mechanism, Whereby the rate of fire of said gun may be varied in accordance-with the force so stored and transmitted.

10. In a gun adapted for automatic fire and provided with a reciprocating bolt and independent buifer mechanism therefor, means including a compressible member actuated by the axial displacement of said mechanism'to store an amount of the bolt recoil force and to return said amountdirectly to said bolt to accelerate its return speed.

11. In a gun adapted for automatic fire a reciprocating bolt and independent butler mechanism therefor, means including a compressible member actuated by the axial displacement of said mechanism to store an amount of the bolt recoil force and to return said amount directly through said mechanism to said bolt to accelerate its return speed.

12. In a gun adapted for automatic fireand provided with a reciprocating bolt and ilidable bufi'er mechanism therefor, means including a compressible member actuated by said mechanism to store a controllable amount of the bolt recoil force and to return said amount to said bolt to controllably accelerate its return speed.

13. In a gun adapted for automatic fire provided with a moving bolt, and whoserate )f fire is predeterminedly set by an ad ustnent of a reciprocable bolt recoil buifer mechnism, means to store a portion of the bolt re- :oil energy transmitted to but unabsorbed by aid mechanism for return to said bolt in acelerating the return speed thereof to its losed position; and means aligned with said :iechanism to vary the amount of energy so tored whereby the rate of fire of said gun is ontrolled.

14. In a gun adapted for automatic fire rovided with a moving bolt, and whose rate f fire is predeterminedly set by an adjustient of a bolt recoil buffer mechanism,

leans including a compressible member in rolongation of said mechanism to store a )rtion of the bolt recoil energy transmitted but unabsorbed by said mechanism for return to said bolt in accelerating the return speed thereof to its closed position; and means comprising a screw to vary at will the amount of energy so stored whereby the rate of fire of said gun is controlled.

15. In a gun adapted for automatic fire provided with a moving bolt, and whose rate of fire is predeterminedly set by an adjustment of a reciprocable bolt recoil buffer mechanism, means coaxial with said mechanism to store a portion of the bolt recoil energy transmitted to but unabsorbed by said mechanism for return to said bolt in accelerating the return speed thereof to its closed position; and threaded means to vary the amount of energy so stored whereby the rate of fire of said gun is controlled in definite ratio of recoil energy so stored and returned.

6 In a gun adapted for atuomatic fire provided with a moving bolt, independently mounted buffer mechanism therefor, and with recoil compensation normally reducing the rate of fire, means to store a portion of the recoil energy of the bolt unabsorbed by said mechanism, and to counter return the same directly to said bolt whereby the return velocity thereof is accelerated with consequent increase infire rate.

In a gun provided with a reciprocable bolt and adapted'for automatic fire at a rate elow normal by a recoil compensating device the combination of means to arrest the rearward movement of said bolt; and means influenced by said arresting means to accelerate the forward movement of said bolt to re establish the normal rate of fire.

18. In a gun adapted for automatic fire and provided with a butter as well as with a muzzle recoil compensating device reducing the normal rate of fire, means to vary the'rate of fire in accordance with the accelerated return velocity imparted by the bufi'er mechanism directly to the reciprocating parts through the force of the excess energy unabsorbed by said mechanism from recoil, said means including compression members coactive with said bufler mechanism.

19. In an automatic gun provided with a recoil compensating device adapted to reduce the normal rate of fire and further provided with-a reciprocating bolt and buffer mechanism therefor, means to'store a portion of the bolt recoil force suificient to accelerate the return velocity of said bolt and to transmit said stored force directly to said bolt through saidbuffer mechanism, wherebv the rate of fire of said gun may be increased.

20. In an automatic gun provided with a recoil compensating device adapted to reduce the normal rate of fire andfurther provided with a reciprocating bolt and independent buffer mechanism therefor, means including a compressible member actuated by said mechanism to store an amount of the bolt recoil force and to return said amount to the amount I speed and reestablish vice the combination directly to said bolt to accelerate its return the normal rate of fire.

21. In a gun provided with a reciprocable bolt and adapted for automatic fire at a rate aelow normal by a 'recoil compensating device the combination of means to arrest the rearward movement of said. bolt; and adjustable means influenced by said arresting means to controllably accelerate the forward movement of said bolt to reestablish the normal rate of fire.

22. In a gun provided with a reciprocable bolt and adapted for automatic fire at a rate below normal by a recoil compensating deof means to arrest the rearward movement of said bolt; and tension means influenced by said arresting means to variably accelerate the forward movement (f f said bolt to reestablish the normal rate of ire.

23. In a gun provided with a reciprocable bolt and adapted for automatic fire at a rate below normal by a recoil compensating device the combination of buffer means to arrest the. rearward movement of said bolt; and

- means influenced by said buffer means and acting therethrough to accelerate the forward movement of said bolt to reestablish the normal rate of fire.

24. In a gun provided with a reciprocable bolt and adapted for automatic fire the combination of independently mounted means to arrest the rearward movement of the bolt upon impact therebetween; and means coaxial with and influenced by said arresting means to freely accelerate the forward movement of said bolt through the arresting means.

25. In a gun provided with a reciprocable bolt and adapted for automatic fire the combination of independently mounted means to arrest the rearward movement of the bolt upon impact therebetween; and means in prolongation of and influenced by said arresting means to instantaneously and directly accelerate the forward movement of said bolt throu h the arresting means.

.26. n a gun provided with a reciprocable bolt and adapted for automatic fire the combination of reciprocable and independently mounted means to arrest the rearward movement of the bolt upon impact therebetween and means influenced by said arresting means to positively and directly accelerate the forward movement of-said bolt through the reciprocation of said arresting means.

27. In a gun adapted for automatic fire and provided with a reciprocating bolt and a back plate, means to arrest the rearward movement of said bolt and to accelerate the forward movement thereof, said means independently mounted with respect to said bolt and comprising back plate, a buffer mechanism slidable in said casing-and adapted to be moved in one a casingsecured to saidmeaave direction by said bolt; stops for said mechanism to limit the movement thereof, a closure for-the outer end ofsa'id casing, and means between said closure and said mechanism to move the'latter in. the opposite direction.

28. In a gun adapted for automatic fire and provided with a reciprocating bolt and a back plate, means to arrest the rearward movement of said bolt and to accelerate the forward movement thereof, said means in- I dependently mounted with respect to said bolt and comprising a casing secured'to said back plate, said casing and adapted to be moved in one direction by said bolt, stops for said mechanism to limit the movement thereof in both directions, a closure for the outer end of said casing, closure and said mechanism to move the latter in the opposite direction.

29. In a gun adapted for automatic fire and provided with a reciprocating bolt and a back plate, means to arrest the rearward movement of said bolt and to accelerate the forward movement thereof, said means independently mounted with'respect to said bolt and comprising a casing secured to said back plate, a buffer mechanism slidable in saidv casing and adapted to be moved inone direction by said bolt, stops for said mechanism to limit the movement thereof, an adjustable closure for the outer end of said casing, and means between said closure and said mechanism to move the latter in the opposite direction with avelocity in accordance with the adjustment of said closure.

30. In agun adapted for automatic fire and provided with a reciprocating bolt and a back plate means to arrest the rearward movement of said bolt and to accelerate the forward movement thereof, said means independently mounted with respect to said bolt and comprising a casing secured to said back plate, a buffer mechanism slidable in said casing and adapted-to be moved in one direction by said bolt, stops for said mechanism to hmit the movement, thereof, an adjustable closure for the outer end of said rovided with' a reciprocablt bolt and adapte for automatic fire at a predetermined rate the combination of recip rocabl means to arrest the rearward move mentof said bolt; and meanscoaxial wit] and influenced by said arresting means ti accelerate the forward movement of saie bolt to increase said predetermined'rate 0 32. In a gun provided with a reciprocabl bolt and adapted for automatic fire ata pr determined rate the combination of slidab] a buffer mechanism slidable in and tension means between said said bolt; and

sion by the sliding of said means to arrest the rearward movement of means placed under compresone direction, said means to accelerate the forward movement of said bolt to increase said predetermined rate of fire 33. n a gun provided with a reciprocablo bolt and adapted for automatic fire at a predetermined rate the combination of slidable means to arrest the rearward movement of means placed under compression by the slidin of said arresting means in one direction sai means to accelerate the forward movement of said bolt to increase said predetermined rate of fire; and an adjustable plug for changing the tension on said compression means whereby the increase in the rate of fire may be varied.

In testimony whereof I aflix my signature.

RICHARD M. CUTTS.

arresting means in

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