US 2599265 A
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W. E. LEEK June 3, 1952 ACCURACY SHOOTING REST WITH RECOIL AZSORBING MEANS Sheeus-Sheet 1 Filed June 27, 1950 a RE 0L T.. NE M m June 3, 1952 W. E. LEEK ACCURACY SHOOTING REST WITH RECOIL. ABSORBING MEANS Filed June 27, 1950 4 Sheets-Sheet 2 0 0/ o o o o l2 /4 0 U9 (E0 0 o o g o o 0 1 01 O O O O INVENTOR.
WAYNE E. LEEK ATTORNEYS June 3, 1952 w, LEEK 2,599,265
ACCURACY SHOOTING REST WITH RECOIL ABSORBING MEANS Filed June 27, 1950 4 Sheet-Sheet s Mum g; INVENTOR.
WA m5 E. A [5K June 3, 1952 w. E. LEEK 2,599,265
ACCURACY SHOOTING REST WITH RECOIL ABSORBING MEANS Filed June 27, 1950 4 Sheets-Sheet 4 Y K m g 5 aw R L f m a w M v mm 0 k 5 g U MFR w\\\\ Nm w. v/ A A H imfiwz Q W q 8 H Patented June 3, 1952 ACCURACY SHOOTING REST WITH RECOIL ABSORBING MEANS Wayne E. Leek, Ilion, N. Y., assignor to Remington Arms Company, Inc., Bridgeport, Conn., a
corporation of Delaware Application June 27, 1950, Serial No. 170,590
This invention relates to a device for testin the accuracy of firearms and has particular application to the final inspection testing of finished newly manufactured firearms.
As the final stage in the functional testing of finished firearms, particularly rifles, it is desirable to fire a number of rounds of ammunition to determine that the arm will shoot accurately and consistently. Any functional defect in barrel, action, or stock will usually be reflected in the size of the group such shots make upon a target. When accuracy shooting is done by a human shooter, many errors and inconsistencies enter the picture. Being human, the shooter is subject to fatigue and as he becomes fatigued both his judgment and his shootin ability are lessened. Particularly with high power centerfire rifles, an accuracy shooter must be limited to firing not more than about ten tests an hour or his work will be absolutely unreliable.
Human errors in shooting have also required many rounds of firing before significant results could be obtained to serve as a guide for gun and ammunition designers in standardizing mmunition characteristics and in studying the effect of design changes, of barrel vibrations, and the influence of the bedding of a rifle in the gun stock.
Previous attemps to eliminate the human factor have all been doomed by the fact that the mechanical rests utilized introduced their own errors due to the method of clamping the arm and, in all cases, the machine rest shooting characteristics of a rifle were radically different from the characteristics noted when fired in the normal way, As a result, human shooters have usually been used for accuracy testing of finished rifles.
By reason of the difference in human and prior machine rest shooting characteristics, it has also been the usual practice for an expert shot to fire a number of shots and appropriately adjust the sights to make the point of impact and the line of sight coincide. A shooting rest in which a gun might be supported and fired without shifting its normal point of impact would obviously permit the gun to be fired for five to ten rounds to establish the center of impact of its normal group, and with the rifle still so held the sights might be adjusted to cause the line of sight to pass through the center of the normal group.
The object of this invention is to produce a firearm testing device into which a firearm may be inserted nd in which it may be fired repeat- 2 edly without shiftin in the device and without requiring re-aiming.
It is a further object of this invention to produce a firearm testing device in which a firearm may be fired with results and grouping characteristics practically identical with those which will be secured by the best human shooters in the best physical condition.
An additional object which is practically a prerequisite to the attainment of the other objectives is the provision of such a device which does not subject the firearm to any unusual stresses or strains which might tend to distort or even fracture gun stocks or tend to cause the firearm to shift in its supports.
I contemplate that these objectives may be best achieved by clamping the gun at buttstock and fore-end rigidly to a light weight rigid frame which is supported for recoiling movement upon balls rolling in V-tracks. During the period in which the bullet is passing through the barrel the recoil of this frame is opposed only by the forces of inertia and friction. Thereafter, the frame is gradually decelerated and returned to its original position.
The exact nature of the invention as well as other objects and advantages thereof will more clearly appear from consideration of the following specification, referring to the attached drawings in which:
Fig. 1 is a top plan view of my device.
Fig. 2 is a vertical longitudinal sectional view taken on the line 2-2 of Fig. 1.
Fig. 3 is a partial front end elevational view.
Fig. 4 is a partial vertical cross-sectional View on the line 4-4 of Fig. 2.
Fig. 5 is a side elevational view of the recoiling frame.
Fig. 6 is a schematic drawin of the electrical and pneumatic circuits employed.
Fig. 7 is a schematic drawing of the electrical circuit of a suitable time delay relay.
Fig. 8 is a partial cross-sectional View on the line 8-8 of Fig. 4.
Referring to the drawings by characters of reference, it may be seen that my invention comprises a recoiling frame I, shown in Fig. 5, generally of channel form, in which a firearm may be received. At the forward end of the frame a pair of plates 2 and 3 are supported to define a V-channel in which the fore-end may rest. Toward the rear end of the channel a socket 4 is arranged to receive a, V-block 5 in which the lower face of the buttstock may rest. To assist in accommodating various gun models, several gun trigger after the gun has been clamped in the upper frame. Obviously, energization of the solenoid will serve to pull the trigger and fire the gun, after which the spring 49 will reposition the pin clear of the trigger. The solenoid may be energized by appropriate means to be later described.
For testing the low and medium powered rifles it is unnecessary to provide any means to decelerate the top frame as the forces of friction and inertia will readily absorb the recoil. Rifles of such calibers as .22 Hornet, .222 Remington, and .257 Remington-Roberts may be so tested. Upon firing, the normal forces of recoil tend to move the top frame rearwardly and, for a small fraction of an inch, it will usually slide over the balls. Thereafter, the balls commence to roll and the ball 40, as soon as it rotates at all, pulls loose from the magnet. As a result of the sliding movement over the balls, they will reach their stops first when the top frame is returned, manually or otherwise, to its normal forward position. The top frame should be caused to slide back to its original position in engagement with the stop abutment 31.
To insure that the top frame is always in the same position upon firing, a switch 50 may be mounted on the lower frame with its actuating plunger 5| in position to be engaged by a cam block 52 supported on the top frame. If this switch is wired in series with the firing solenoid and is closed only when the plunger is depressed, it will be impossible to fire from any other than the foremost position.
For all the higher powered loads, it is essential to provide means in addition to the rubber block to decelerate the upper frame. For arms of any power it is convenient to have automatic means to return the top frame to its correct position after each shot is fired. These means can readily be combined in one unit by the utilization of a double acting air motor 53 positioned, preferably, in axial alignment with the barrel of a firearm clamped in the frame with the piston rod 54 arranged to impinge upon a plate 55 supported on the top frame.
In the preferable operating cycle the air motor will be started rearwardly slightly before the gun is fired and will continue to move rearwardly at a rate which is less than the normal recoil velocity of the firearm. Thus, the firearm which is accelerating rearwardly will overtake the air motor and in attempting to accelerate the air motor will dissipate much of the recoil energy, permitting a smooth shockless deceleration of the top frame. Y
After the assembly reaches its rearmost position the air motor is reversed, returning the top frame to its normal forward position and holding it there by air pressure until just prior to the actuation of the firing solenoid for another shot. In either direction of motion the air motor is driven by air pressure acting on one face of the piston and the velocity attained is determined by the rate at which trapped air is released from the space behind the piston. The timing of the motion of the air motor is controlled by electrical circuit means which will be described in more detail by reference to Fig. 6.
In regard to the general features of mechanical construction, it is of importance that all units be as rigid as possible and that the weight of the recoiling upper frame be reduced to the absolute minimum. This latter end can be achieved by utilizing aluminum as the material of construction, all of the lightly stressed areas being skeletonized to the maximum extent possible. A welded construction of built-up plate and channel sections is a convenient and. economical mechanical form.
Although the recoil forces are resisted in direct line with the barrel, there appears to be an occasional tendency to muzzle jump with some arms which may tend to rock the upper frame about the balls on which it rolls. This tendency may be kept under control by mounting guard rails 56, 51, 58, and 59 on the upper frame and securing over each rail a roller bearing 60 fixedly mounted on the lower frame.
As has been noted, the lower frame should be made as rigidly as possible and the weight of this frame is immaterial except from a standpoint of ability to move it around. For a factory installation, it may be very heavy and should preferably be mounted with capacity for positioning in elevation, azimuth, and height above the floor or relative to the opening into a shooting range. Conveniently, it may be mounted upon a machine base having the type of controls and adjustments typical of industrial planers, radial drill presses, or some types of millers or grinders. Details of such a mounting are not disclosed for they form no part of the present invention.
Referring now to the air-electric circuits shown in Fig. 6, a brief functional review of the end to be accomplished may aid in understanding the detailed wiring diagram.
To insure that the operator must have his hands and body in a safe position, it is desirable to provide a suitably located operating station with two operating buttons 61 so spaced that the operator must use one hand for each button. Pushing these buttons should initiate the action of all electrical circuit elements and should lock in the circuit for the normal duration of the operating cycle through the agency of time delay relay 62 and contactor 63. Operation of the buttons should also immediately start the piston rod 54 to moving rearwardly. After a short time delay, approximately of a second, the firing solenoid 45 should be actuated by time delay relay 64 and after the arm has fired and the top frame has reached its rearmost position, the air motor may be reversed and returned by means including time delay relay 65 and double acting valve 66. In the event of a hangfire or misfire, time delay relay 5! is arranged to take control of the air motor and return the piston rod 54 to prevent a completely free recoil of the top frame. A switch 68 mounted on the lower frame and actuated by a cam 59 on the top frame is arranged to shift the control function from relay 6! to 65 when the gun fires and the top frame recoils.
The switch 50 previously referred to is Wired in series with the firing solenoid 45 to prevent firing in case the top frame is in an other than its correct position.
To insure that the unit will not be operated without adequate air pressure, an automatic pressure switch 69 is arranged in the airline and controls the supply of power to all units.
The air clamps 22 on the forestock are actuated by a solenoid operated valve I0 which is energized as a result of closing the switch 1| when the buttstock clamp 19 is closed. As a further safety feature, an automatic air switch 12 is attached to the air line reaching the air clamps and this switch is arranged in series with the push buttons 6| to insure that the operating cycle will not 'be initiated unless all of the clamps are closed.
9 usually causes the frame to slide a short distance before the balls commence to rotate. The high powered loads will cause the top frame to recoil at a faster rate than the normal rate of the air motor and the piston rod will be overtaken.
In the event that either firearm or ammunition is defective and hangfire is encountered, it is preferable not to allow the top frame to recoil without opposition after the air motor has substantially completed its rearward excursion. Accordingly, it is the function of the time delay relay 6'! to return the air motor before it reaches the rear limit of its movement in the event that the arm has not fired by the time 0.4 second has elapsed. Switch 68 remains in the position shown in Fig. 6 until the top frame has recoiled and when time delay relay 61 times out a circuit is completed through contacts D and F thereof to the actuating coil 82 of the air valve 66. This action reverses the air motor and it is returned by air pressure at a rate determined by the setting of bleeder valve 83.
If the arm fires normally and the top frame recoils the micro-switch 68 will transfer control of the air motor from time delay relay 61 to time delay relay 65 which does not time out until substantially 0.8 second has elapsed. In this length of time the top frame and the air motor under the combined urging of compressed air and the recoil forces of the top frame will have reached a rearmost position and come to rest. When relay 55 times out the air motor will be reversed to return air motor and carriage to a normal forward position. Valve 66 is preferably not of a spring return type and, hence, will remain in either position, after one coil has been de-energized, until the opposite coil is energized. This insures that the operation of switch 68, although occurring in mid stroke of the air motor, does not interfere with the smooth movement thereof.
Relay 62 preferably is adjusted to time out just after the top frame has been returned to forward position and releases the interlock relay 63, thus opening the by-pass around the firing buttons and resetting all relays. Since the valve 66 remains in the position to which it was last drawn, the air motor will continue to press the top frame forwardly against the stop block 31. It has already been noted that the top frame usually slides rearwardly on the balls before they commence to roll. As a result, when the top frame returns toward its forward position the balls reach their stops before the top frame does and the final forward movement of the top frame is a sliding movement. Thus, the return of the top frame to its identical starting position is not influenced by the possibility that foreign material may have accumulated on a face of a ball stop and prevented the ball from reaching its identical position. The only other possibilities of a nonidentical firing position are practically ruled out by the fact that the balls have virtually line contact with the V-tracks in which they roll and are therefore self-cleaning; and by the fact that the clamps retain the arm against any shifting 10 found to have a satisfactory grouping characteristic, the alignment of its sights with the observed point of impact may be checked and, if necessary, corrected without removing the ride from the mount.
While I have quite specifically illustrated and described a preferred embodiment of my invention, it will be obvious that variations may be made therein without departing from the spirit. of my invention. For an exact statement of the limits thereon, reference may be had to the appended claims.
l. A machine rest for firearm testing comprising in combination a framework; means to clamp a firearm to said framework; a mounting for said framework including a track; rollable means engaged between said framework and said track supporting the framework with capacity for recoil from a predetermined starting position relative to said mounting; means to return said framework to said starting position after completion of said recoil; and electrical control means for said return means arranged to render said return means inoperative to oppose recoil of said framework at the instant of firing and during a free recoil period thereafter at least equalling in time duration the time required for a projectile fired from a firearm clamped to said framework to pass through the barrel of said firearm.
2. A machine rest according to claim 1, said clamping means being constructed and arranged to engage the buttstock and forestock of the firearm without contacting or straining the barrel of said firearm.
3. A machine rest according to claim 2, said framework and said mounting therefor being provided with opposed, parallel, cooperating tracks and with spherical balls received in said tracks upon which said framework is reliably supported.
4. A machine rest according to claim 3, and means associated with said mounting to decelerate and stop the free recoil of said framework after a projectile has passed through the barrel of the firearm.
5. A machine rest according to claim 4, said decelerating means incorporating a pneumatic cylinder, an exhaust outlet from said cylinder, a restricted orifice limiting the escape of air through said exhaust outlet from said cylinder, a piston reciprocable in said cylinder, and control means arranged to position said piston where it will be out of contact with said framework at the instant of firing and during said free recoil period and engaged by said framework at the conclusion of free recoil thereof and thereby propelled into said cylinder to compress the air therein and to force same through said restricted orifice.
A machine rest according to claim 5, including in addition a source of air under pressure and control valve means associated with said pneumatic cylinder arranged to close said exhaust outlet after said framework has recoiled and to admit air from said source into said cylinder to impart a counter recoil movement to said piston and thereby to return said framework to said predetermined starting position.
7. A machine rest according to claim 6 in which said pneumatic cylinder is a double action cylindcr an: in which said control valve means is constructed and arranged for positioning to admit ascends 11 air from said source to move said pistonin either direction; an operator for the. control valve; means arranged to initiate an operating cycle'by positioning said valve to move said piston in' recoiling direction; and firing means mounted on said framework constructed and arranged. to fire a firearm clamped to said framework only after said piston has started tomove in the recoiling direction.
8'. A machine rest according to'claim'7f,.includ ing time delay switching means arranged to be started by a manual operation and electricalioperators for said control valve and. said firin means, said switching means being constructed and arranged to energize said valve operator for positioning said valve means to move said piston in recoilingv direction as soon as said switching means is manually started, thereafter tov energize the operator for said firing means, andthereafter to energize the said valve operator for positioning said valve means to reverse said piston and thereby to return said framework to the predetermined starting position.
9. A machine rest according to claim 8, including an electric switch element in series relation with the operator for said firing means, said switch element being so positioned and arranged relative to said framework and said mounting as to interrupt the circuit to the operator for said firing means except when said framework is in the predetermined starting position.
10. A machine rest according to claim 9; including means arranged to prevent manual starting of said time delay switching means unless said means for clamping a firearm to said framework is fully operative.
11. A machine rest according to claim 10, including' a switch operated by recoil of said framework from the starting position and an auxiliary time delay switching means arranged to be disabled by operation of said switch and arranged to energize said valve operator for positioning said valve means to reverse said piston if the framework does not recoil in response to firing of the firearm immediately after the operator for said firing means has been energized.
12. A machine rest for firearm testing comprising in combination a light weight rigid frame work; means defining a V-groove in said framework arranged to receive the forestock of a firearm; cl'amping means arranged to engage the forestock of a firearm to retain same in said V-groove; abutment means in said framework arranged to be engaged by the buttplate of a firearm; opposed V-block means mounted in the framework and arranged to have clamping engagement with the upper and lower edges of the buttstock of a firearm; mounting means arranged to accurately position said framework in a predetermined position in which a firearm engaged therein may be fired; means arranged to accurately return said framework to said predetermined position after each time a firearm may be fired therein, and control means arranged to render said return means inoperative to oppose recoil of said framework at the instant of firing and during a free recoil period thereafter at least equalling in time duration the time required for a projectile fired from such firearm to pass through the barrel thereof.
13-; A machine" rest according to claim 12, said mounting means being provided with a plurality ofsubstantially mutually parallel V-groove tracks; spherical. balls received in said tracks for rolling movement therein; and cooperating opposed tracks on said framework adapted to be rollingly supported on said balls.
14. A machine rest according to claim 13, and a magnetic retaining device on said mounting arranged to releasable retain at least one of said balls in a position in the track corresponding to said predetermined position.
15. A machine rest according to claim 14, and pneumatic buffer means on said mounting arranged to be engaged by said framework during recoiling movement thereof and to decelerate and stop' such movement.
116; A machinerest according to claim 15, a source of air under pressure; and pneumatic piston means operated by said air under pressure arranged to return said framework to said predetermined position after recoiling movement thereof.
17'. A machine-rest according to claim 16, said pneumatic buffer' and said pneumatic piston means being combined in a single pneumatic cylinder mounted on said mounting means and provided with a piston arranged to be engaged by said'framework'; and valve means arranged to selectively restrict the escape of air from said cylinder during recoil of said framework and the piston engaged thereby orto admit air from said source into said cylinder to return said piston and said framework to said predetermined position.
13. A machine rest for firearm testing includmg in combinationa framework arranged to support a firearm; mounting means for said framework arranged to support and guide said framework during recoil thereof in response to the firing of a firearm supported thereon; a decelerating piston: arranged to be engaged by and to yieldably oppose recoil of said framework; means to initiate: recoil movement of said decelerating pistonat a rate less than the normal recoil velocity of the; framework; and means on the framework to fire a firearm supported thereon after recoiling movement of the decelerating piston has been started.
. WAYNE E. LEEK.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number 7 Name Date 1,367,353 Craig Feb. 1, 1921 2,378,545 Eraser June 19, 1945 2,469,400 Newell May 10, 1949 FOREIGN PATENTS Nun'iber Country Date 5641539" Germany Nov. 19, 1932 OTHER REFERENCES Publication: Scientific Shooting Gallery, in Popular Science Monthly, July 1935, pages 20, 21
i andl05. Copy in Div. 36, U. S. Pat. Ofiice.