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Publication numberUS3866516 A
Publication typeGrant
Publication dateFeb 18, 1975
Filing dateJul 30, 1973
Priority dateJul 30, 1973
Publication numberUS 3866516 A, US 3866516A, US-A-3866516, US3866516 A, US3866516A
InventorsFrisoli David M
Original AssigneeFrisoli David M
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Semi-automatic piston employing a pivotally, slideable member
US 3866516 A
Abstract
There is disclosed an automatic weapon which utilizes structure providing an improved action. A slide member is coupled to a barrel member. The barrel is rigidly secured to a frame and does not move during firing. The slide is caused to move during recoil such that it pivots and is urged to move a relatively large distance in a short time thus providing an improved retardation action and further compensating for barrel rise during recoil.
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nite States Patent Frisoli [4 1 Feb. 18, 1975 SEMI-AUTOMATIC PISTON EMPLOYING A PIVOTALLY, SLIDEAIBLE MEMBER [76] Inventor: David M. Frisoli, 2 Homestead Rd., Edison, NJ. 08817 [22] Filed: July 30, 1973 [21] Appl. No.: 383,592

[52] US. Cl. 89/190, 89/198 [51] llnt.CI. ..F41d 3/06,F41d 11/12 [58] Field of Search 89/180, 184. 190, 196

[56] References Cited UNITED STATES PATENTS 5/1922 Reifgraber 89/184 OTHER PUBLICATIONS George M. Chinn, The Machine Gun, 1951, pp. 160-169.

Primary ExaminerStephen C. Eientley Attorney, Agent, or FirmArthur L. Plevy [57] ABSTRACT 10 Claims, 6 Drawing Figures EST PATENTED 3.866516 SHEET 2 OF 2 Fig- 3 Z0 SEMI-AUTOMATIC PISTON EMPLOYING A PIVOTALLY, SLIDEABLE MEMBER BACKGROUND OF INVENTION This invention relates to automatic weapons and more particularly to an improved operating action utilized in such a weapon.

Basically, there exists a wide variety of guns or automatic weapons. In its wider sense, the term gun can include any kind of firearm from a pocket pistol to a heavy cannon. Although guns can be placed in many categories, a convenient way of describing them would be those having large bore barrels and those having small bore barrels. The function of a gun barrel is to enable the projectile or bullet to reach a suitably high initial velocity in a very shor time. In an automatic weapon, all the functions of firing and reloading are performed by the gun or weapon itself. Basically, these functions can be described as firing the cartridge, withdrawing the bullet, ejecting the spent cartridge case, cocking the hammer, forcing the bullet forward and inserting a fresh cartridge into the chamber so that the next show can be fired. The energy for performing these functions is either provided by the pressure of the gas produced by the firing of the cartridge or bythe recoil of the weapon.

Coupled with the desire to automate the weapon for rapid firing, there is a further desire to maintain or provide an accurate weapon. Accuracy is difficult as the caliber of the bullet or projectile increases because of the recoil of the weapon and the difficulty in maintaining the weapon steadily. This is especially true in pistols or hand-held guns. It is well known that the gas pressure develops when the gun is fired thus producing high stresses in the interior of the barrel. For this reason, monobolc (one piece) barrels are used only for guns of very small caliber.

In most large caliber guns, the barrel moves or recoils to absorb the energy produced when the bullet is ignited. Besides barrel movement in the horizontal plane, there is also vertical movement which causes the barrel to rise during the firing.

These factors, as well as others, serve to adversely affeet the accuracy of the weapon.

The following discussion will concentrate on a large bore pistol such as a 0.45 caliber pistol as compared to a 0.22 caliber or a conventional monobolc pistol. This type of firearm has been in use for many years employing automatic action. Perhaps the earliest example of such a pistol is evidenced by U.S. Pat. No. 580,924 entitled FIREARM by J. M. Browning, patented Apr. 29, 1897. This patent shows a gun with a completely automatic action including a moveable barrel and slide. As indicated, accuracy has always been a concern and there exists many improvement patents whereby they have included mechanisms to compensate for the movement of the barrel during firing. Therefore, the prior art shows a number of patents whereby the barrel is mounted so that its breech end swings slightly downwardly upon recoil and so on. These patents include compensating bushings and other devices to maintain accuracy.

Examples of such typical patents showing certain prior art gun configurations are evidenced by U.S. Pat. No. 3,158,064 entitled FIREARM WITH A PIVOT- ABLE BARREL HAVING A SPHERICAL HUMP ENGAGING A SLIDE MEMBER by D. W. Charron,

patented on Nov. 24, 1964 and U.S. Pat. No. 3,411,408 entitled MOUNTING STRUCTURE FOR PISTON BARRELS by FA. Pachmayr, et al., patented on Nov. 19, 1968.

It would be accurate to say that in most of the prior art guns, the barrel moves and is not fixed with respect to the receiving part of the pistol which commonly includes the handle and the trigger mechanism. When it is stated that the barrel moves, it is meantthat it moves intentionally due to the nature of the gun design. Accordingly, in such pistols, the barrel is slidably mounted on the receiving portion of the gun. The inherent movement of the barrel, as indicated above, affects accuracy of the gun in that in order to assure true aim in an automatic weapon, the movement of the barrel has to be the same for each shot and so on.

It is an object of the present invention to provide an automatic large bore piston employing a stationary barrel or a barrel which can be integrally formed as a part of the receiving portion of a gun. In such a gun, a slide mechanism operates during recoil to perform, by its movement, the steps indicated above as normally associated with an automatic weapon.

It is a further object of the present invention to provide a moveable slide arrangement whereby the slide is constrained to move in an opposite direction from the direction of the projectile released by the gun while simultaneously moving upward. This composite motion exerts a force on the stationary barrel which tends to push the same downwardy or in a direction to compensate for the undesired barrel rise.

These and other objects are provided in a new gun mechanism capable of automatically firing a successive number of large caliber bullets while maintaining relatively identical accuracy and velocity for each shot.

BRIEF DESCRIPTION OF PREFERRED EMBODIMENT A projectile firing gun includes a frame assembly for a barrel rigidly secured to the frame and a slide covering a portion of said barrel and mounted for movement between a first and a second position. The barrel has at least one lug assembly located near the muzzle end and positioned within a lug accommodating aperture located on a cooperating surface of said slide. Means are located on the breech end of the barrel which couple the slide to the barrel and permits the slide to pivot with respect to the barrel when the slide moves from said first to said second position. The upward movement of said slide being due to said pivoting motion as determined by a surface contour of said lug.

BRIEF DESCRIPTION OF FIGURES FIG. I is a cross sectional view showing an automatic weapon according to this invention.

FIG. 2 is a side elevational view of the gun of FIG. 1 showing the slide mechanism in a maximum recoil position.

FIGS. 3 through 6 are a series of drawings showing the sequence of operation and motion of the various parts of a weapon according to this invention.

DETAILED DESCRIPTION OF DRAWINGS Referring now to the figures, it is to be understood that the invention is adapted to be used with a handheld automatic firearm capable of firing a large caliber bullet.

FIG. 1 shows a side cross sectional view of the firearm which includes a frame 1, trigger '9, trigger guard 11 and a hammer7. The frame 1 is integral with the barrel portion 14 of the gun.

conventionally, the frame 1 includes a handle 12 as shown asa grip which includes the trigger guard 11. The handle is hollow and accommodates a cartridge or magazine with a spring for feeding the bullets into the chamber during operation of the weapon. In this gun, the barrel portion 14 does not and cannot move with respect to the frame 1 or handle 12. These components or formed separately and later welded or secured together. The important initial aspect being that the barrel portion 14 of the gun is stationary with respect to the frame 1.

Slideably mounted on the barrel portion 14 of the frame I is a slide member 4. The slide, as will be seen, cooperates with a breech block or bolt assembly.

The slide assembly 4 is slideably mounted for rearward or recoil movement with respect to the barrel portion 14, and at the same time can pivot about a stabilizer skid point located at the rear end of the frame 1 near the handle or breech portion of the gun. The skid stabilizer, as will be explained, forms a pivot point which permits the slide to move upward while moving away from the firing direction of the projectile or bullet 20. The bullet 20, which may be a 0.45 caliber, is shown seated in the front portion or firing chamber of the central bore 15 of the barrel portion 14.

As can be seen from FIG. 1, the hammer 7 is cocked and can be released by activation of the trigger 9. As the trigger 9 is squeezed, the bar 21 is moved backward. A projection on the arm releases a hammer trip member 22. The hammer is forced toward the firing pin 24 by means of the energy stored in the hammer spring 23. The hammer conventionally strikes the firing pin 24 which is mounted coaxially with the breech block 25. The firing pin is forced towards the bullet by the hammer and strikes the bullet causing ignition as it is conventionally known.

The above described mechanism for operating a hammer and firing pin arrangement is known and can be implemented in a variety of different ways.

The main concern of this application, as has been indicated above, is to describe the unique action as to the movement of the slide member 4 with respect to the barrel portion 14.

Due to this unique movement and due to the fact that the barrel is entirely stationary with respect to the frame, the accuracy of a large bore pistol has been increased. This further effect is provided together with extreme reliability as compared to the prior art units.

If reference is made to FIG. 2, there is shown the slide portion 4 retracted rearwardly from the barrel portion 14. The distance designated as D shows the amount of backward movement during the recoil action by the slide member with respect to the barrel portion 14.

Before further describing the basic components of the gun, a description of the unique action will be had by referring to FIGS. 3 through 6 which in essence are simplified diagrams showing the sequence of events as they occur during firing.

' can'be integrally formed by means of a single casting DESCRIPTION or FIG. 3 GUN IS IN CLOSED POSITION AND READY TO BE FIRED There is shown the bullet 20 in the firing chamber portion of the central barrel bore 15. The slide 4 is maintained about the barrel portion 14 and the extreme front edge 30 of the slide 4 is closest to the gun sight 31 which is rigidly affixed to the barrel portion 14 of the gun near the muzzle. Also shown on the barrel portion are a first and second lugs respectively designated as 32 and 33. These lugs have angled front surfaces and cooperatewith similar indentations formed in W the slide portion of the gun. Thus, as can be seen, the lugs 32 and 33 are seated within the lugaccommodating apertures associated with the slide portion of the gun and this is in the closed position. The surfaces of the lugs are inclined at an acute angle with respect to the barrel aperture. The angle used is about 65 but other angles can be used as well, the important factor being that the angle is such to prevent locking the slide to the barrel.

Also shown is a bolt assembly or breech block 24. The bolt 25 has a central aperture, as indicated, which accommodates the firing pin mechanism 24. The bolt as positioned is moveable with respect to the fixed barrel l4 and is coupled to the slide portion by means of lugs 35 and 36 located on the top surface of the bolt or breech block 25. The lugs are shown as generally rectangular in shape as compared to the inclined surface of lugs 32 and 33 previously mentioned.

FIG. 3 shows the hammer 7 is in direct contact with the firing pin. The following action occurs immediately when the firing pin 24 is pushed forward by the hammer. The spring 35 associated with the firing pin is compressed. The end of the firing pin strikes the back surface of the bullet 20. As is known, the powder is ignited and the projectile is released from the shell or case of the bullet. At the moment of ignition, tremendous gas pressure develops causing the release of large amounts of energy. Essentially, one is talking about the conversation of momentum in that the bullet which was stationary is, due to the explosion, propelled with a large velocity. This velocity together with the bullets mass imposes a large force in the opposite direction upon the gun thus causing recoil. The gun is forced back and because the grip is below the barrel, the users hand is rotated upwardly.

DESCRIPTION OF FIG. 4 THE BULLET IS PROPAGATING DOWN THE BARREL OF THE GUN As shown in FIG. 4, the projectile portionof the bullet 20A is separated from the shell 20B and is being propelled at great velocity through the barrel. A force is exerted upon the breech block 25 which moves rearwardly due to this force imposed by the moving projectile. The movement of the breech block or bolt 25 is at a 3 degree angle with respect to the center line 40 of the barrel. As the breech block is forced back, it pulls the slide 4 with it due to the action of the lugs 35 and 36. The slide is permitted to move due to the location of a stabilizer skid 41 which couples the slide to the barrel and rides in a channel 42 located in the inside side wall of the slide 4. The channel is shown in a solid line for the sake of simplicity. The term stabilizer skid" is used to indicate action. Basically, all one needs to provide is a projection on the frame, which projection rides in a channel located on the inside surface of the slide member. In this way, the backward motion of the slide member is constrained by the dimensions of the channel as is the pivoting of the firing arm. While a particular mechanism is shown, it is realized that many mechanisms can be employed to permit the slide to move as described with respect to the barrel.

The movement of the slide 4 can be seen from a comparison of FIGS. 3 and 4 and by noting the position of the skid 41 within the channel 42. It is also seen that the slide is moving back and at the same time is pivoting about the skid location 41. This pivoting is in an upward direction and occurs when the gun is firing and the bullet is traveling down the barrel bore. The slide as it is pivoting is also moving back across the lugs 32 and 33. This motion causes a downward force to be applied to the fixed barrel portion 14 of the gun. The downward force compensates for the barrel rise which is inherent due to the force developed during the firing of the gun. The motion of the slide with respect to the barrel causes a compensating force to be directed on the barrel, the force tends to maintain the barrel rise station'ary during firing.

DESCRIPTION OF FIG. 5 THE PROJECTILE HAS LEFT THE MUZZLE FIG. 5 shows the position of the slide 4 as the bullet is leaving the muzzle of the gun. In FIG. 5 the projectile is shown leaving the muzzle end of the barrel portion 14. The slide is shown in its maximum upward position with respect to the barrel portion 14. Accordingly, the lug accommodating apertures associated with lugs 32 and 33 are above the respective lugs. It is noted that the rearward movement of the slide with respect to the muzzle end of the gun is relatively slight but the projectile is discharged from the gun..Essentially, the slide is forced to move a relatively large amount upward for a very small backward motion. This is accomplished by forcing the slide to move over the angled surfaces of the lugs. In fact, approximately speaking, the slide moves to the position shown in FIG. 5 during the first 0.125 inches of backward travel of the bolt 25. As can be seen from FIG. 5, this distance is relatively small. The action of the slide is mainly a pivoting action during this small initial travel. It is further seen that as the bullet or projectile is propagating down the barrel to be released at the muzzle end, the slide is exerting a downward force on the barrel as it is traveling over the lugs 32 and 33. This downward force tends to compensate for the rise of the barrel which occurs as the bullet is ignited and released. Thus, the compensating force on the barrel by slide 4 improves the accuracy of the gun. As shown in FIG. 5, as the bullet is leaving the muzzle, the slide has moved over the lugs 32 and 33 and will continue its backward motion.

DESCRIPTION OF FIG. 6 BACKWARD MOTION OF SLIDE AND AUTOMATIC ACTION OF THE GUN moved to its extreme back position whereby the hammer 7 has been reset or cocked b y the camming surface of the breech block 25. As can be seen from the figure, once the hammer 7 is pushed back to the position shown in FIG. I, it is automatically held in place by member 22. The action of the slide in forcing the hammer downward again also compresses the hammer spring 23 thus a first step for automatic firing is accomplished by this movement.

As is clearly shown in FIGS. 4 and 5 for example, the shell of the bullet 20B is still within the firing chamber 51 of the barrel 15. This shell must be ejected to accommodate an automatic firing process.

Referring to FIG. 2 there is shown a shell ejection port or aperture 53 located on the top surface of the slide 4. It is noted that in FIG. 2 the slide member is in its extreme back position with respect to the muzzle end of the gun.

Now referring to FIG. 6, the hammer 7 is shown ready in position. When a bullet as 20 is in the firing chamber, an extractor pin (not shown) is inserted into the ridge ofthe bullet formed by the back surface ofthe bullet and the cartridge wall. The ridge is shown in FIG. 3 as 70.

The extractor pin is secured to the breech block 25 and as the breech block moves back due to recoil, the casing 208 is pulled along. An ejector pin is situated on the frame assembly 14 and is in the path of the shell as it is drawn back. As indicated, the ejector port 53 moves back with the breech block because of the motion of the slide 4. The ejector pin contacts the shell when the port 53 is aligned with the shell but before the breech block is clear of the cartridge case. The ejector stop causes the bullet to spin and be urged upward and through the ejector port 53 as shown in FIG. 6. The shell 20B is thus ejected. The breech block continues to move back and clears the cartridge case to allow the next bullet 60 to be inserted into position with the bore of the barrel. During return of the breech block, the bullet is pushed into the firing chamber 51 and a new sequence is ready. Thus, two additional steps for automatic firing have been achieved, namely, the shell is ejected and a new bullet or a fresh bullet is moved upward into the barrel area of the gun. The slide must now be returned to the position shown in FIG. 1. This is accomplished by means of the spring 50 of FIG. 1 which operates as the return spring. The return spring 50 is conventional in most automatic guns which incorporate a moveable slide. In any event, the spring being compressed during recoil now returns the slide to its initial position. To further assure that the slide is properly returned, there is shown an actuator arm 71 with a spring 70. The name actuator is used to indicate that if this is not properly returned, the gun cannot be tired. The operation of the arm 71 and the spring is clearly shown in FIGS. 3 through 6 and essentially operates as follows:

As the slide is moved backward, the actuator arm is tilted or raised from the position shown in FIG. 3 to the position shown in FIG. 6 by means of a spring. The entire slide after firing is pushed back towards its initial position by means of spring 50 which is the return spring. As the slide is pushed back towards the muzzle end of the gun by the spring 50, a notch 73 in the slide contacts the projection 74 on the actuator arm 71. This then pushes the actuator arm back into position and assures that the slide is closed in its proper position. The

actuator arm together with its spring also serves to dampen the slamming action of the slide when it is being returned to its quiescent condition. Thus, at the end of the sequence, the weapon is as shown in FIG. 1

and is ready to be fired again and again, completely automatic as described, and until the last bullet is expended.

The above mentioned action was utilized in a pistol as shown. The pistol built was approximately 8 inches long. The slide and the breech block 25 weighed about 14 ounces. The reason for this tremendous reduction in weight without a locking system of the prior art is afforded by the increased retardation available in this firearm. Thus, when the pressure is greatest during recoil (i.e. the bullet is in the barrel but has been fired), the slide 4 moves a larger distance in a short time as compared to the distance moved by the bolt (0.125 inches'as indicated above). This is due to the fact that the slide was caused to move over the inclined surface of the lug. The retardation is also increased by the fact that the bolt is moving relatively horizonally and this movement has to be translated to cause the slide to move upward.

Since the pivoting occurs at the breech end of the gun, then this increased motion occurs at the front; therefore, if more weight were added to the front, the retardation would even be greater.

It is understood that this invention in regard to the above noted action takes advantage of the laws of momentum and conservation of energy. The idea of this invention is to permit the slide to move a relatively large distance upward and back very quickly and during that time when the greatest pressure or force is exerted on the breech block. In this manner, retardation can be obtained quickly and barrel rise is compensated for due to the pressure exerted by the slide on the barrel assembly. It is also'important to note that the barrel assembly is rigidly secured to the frame and the gun sights can now be secured to the barrel assembly so that extreme accuracy can be maintained.

While a particular configuration has been shown for the gun, it is also realized that the principal can be used in any type of firearm and is not necessarily confined to a 0.45 caliber projectile. It is the main purpose of this application to describe the new and improved action and it is realized that the same advantages and benefits and other variations may be made in this invention without departing from the scope thereof. This can be done especially in different types of firearms and the invention should be limited in scope only as determined by the following claims.

What is claimed is:

l. A firearm for firing projectiles, comprising a slide member moveable from a first position to a second position, a barrel assembly integrally formed with a frame assembly, means coupling said barrel to said slide to cause said slide to first pivot upward away from said barrel during recoil when moving from said first to said second position and while said projectile is still in the barrel and furthest away from the muzzle end of said barrel.

2. A firearm, for firing a projectile, comprising,

a. a frame assembly,

b. a barrel assembly rigidly coupled to said frame assembly,

c. a slide assembly adapted to be positioned over said barrel assembly and moveable from a first to a second position, and

d. means coupling said barrel assembly to said slide assembly to cause said slide to pivot upward at a muzzle end of said barrel as said slide is moved from said first to said second position and thence move relatively parallel to said barrel, said slide pivoting upward before said projectile leaves said barrel and beginning when said projectile is furthest away from said muzzle end.

3. A firearm for firing projectiles comprising a slide member moveable from a first position to a second position, a barrel assembly rigidly secured to a firearm frame assembly, means coupling said barrel to said slide to cause said slide to pivot at a breech end of said barrel when moving from said first to said second position during a recoil of said gun due to the firing of a projectile, said barrel having located on a surface thereof near said muzzle end at least one projection having an inclined surface, which projection is accommodated within an aperture on a surface of said slide, said aperture snbstaintially congruent with said projection whereby when said slide member begins to move from said first to said second position, said slide is forced to pivot upward and away from said barrel as it moves over said inclined surface to exert a downward force on said barrel before a projectile is discharged from said muzzle but while it is traveling within said barrel and commencing when said projectile is still in said barrel andfurthest away from the muzzle end of said barrel.

4. The firearm according to claim 3 wherein said inclined surface of said projection is at an acute angle with respect to the center line of said barrel.

5. The firearm according to claim 3 wherein said means coupling said barrel to said slide further include a breech block coupled to said slide and moveable with respect to said housing in a direction relatively parallel to said barrel, said breech block adapted to pull said slide over said inclined surface of said projection.

6. A projectile firing gun including a frame assembly having a barrel rigidly secured to said frame and a slide covering a portion of said barrel and mounted for movement between a first and a second position, said barrel having at least one lug assembly located near a muzzle end of said barrel and positioned within a lug accommodating aperture located on a cooperating surface of said slide, and means located at the breech end of said barrel and coupling said slide to said barrel to cause said slide to pivot with respect to said barrel when said slide moves from said first to said second position, the upward movement of said slide due to said pivoting motion being determined by a surface contour of said lug whereby said upward movement causes a force to be exerted on said barrel to compensate for an undesireable barrel movement due to a movement of said frame when a projectile is fired and before said projectile leaves said barrel but when said projectile is furthest away from said muzzle end.

7. A firearm assembly for firing projectiles comprising a U-shaped slide member adapted to be positioned over a barrel assembly, said barrel assembly being rigidly secured to a firearm frame assembly, said slide member being moveable froma first position to a second position, means coupling said slide member to said barrel assembly to cause said slide member to pivot upwardly initially during said movement from said first to said second position and to then move relatively parallel. to said barrel member, said barrel member having located thereon near a muzzle end a lug having a front surface which is inclined with respect to a barrel center line and directed towards a breech end of said barrel, said slide having a corresponding aperture which is positioned over said lug in said first position and is removed from said lug during said second position so that said lug is not in contact with any part of said slide during said second position,,said inclined surface of said lug causing said slide to pivot upwards and away from said barrel while moving to said second position, and while said projectile is still traveling in said barrel and furthest away from the muzzle end of said barrel.

8. A firearm for firing projectiles including a frame assembly having a handle portion with a barrel portion rigidly secured to said frame assembly and a slide assembly covering said barrel portion and mounted for movement with respect to said barrel from a first to a second position, said barrel having at least one projection located nearer a muzzle end of said barrel as compared to a breech end of said barrel, said projection having a given surface contour and of a given slope with respect to the barrel center line, said projection being accommodated within a projection indentation located on the corresponding surface of said slide so that said projection is within said indentation when said slide is in said first position, and means coupling said slide to said frame assembly to move said slide from said first to said second position to cause said slide to move over said sloped surface contour of said projection as pivoting upwards from said barrel center line, and thence to said second position defined by the complete exposure of said projection due to the movement of said slide, whereby a portion of said barrel including said projection is uncovered when said slide is in said second position, said motion of said slide over said projection causing a downward force on said barrel during recoil occuring while said projectile is still traveling in said barrel and furthest away from the muzzle end of said barrel.

9. The firearm according to claim 8 wherein said means coupling said slide to said frame includes a breech block slideably mounted on said frame for relatively parallel movement with respect to said barrel, said breech block including means coupling the same to said slide to therefore move said slide for a movement of said breech block.

10. A firearm, comprising,.

a. a frame assembly including a handle portion and a barrel portion rigidly secured to said handle portion,

b. a slide member adapted to cover said barrel portion of said frame assembly and capable of moving from a first rest position where said slide is substantially covering said barrel to a second recoil position where a portion of said barrel is exposed and not covered by said slide,

c. a breech block slideably mounted on said barrel portion of said frame assembly and coupling said frame to said slide, said breech block positioned above said handle of said frame and adapted to move relatively parallel to the center line of said barrel portion during recoil, and

d. means forming a projection located on said barrel portion at said muzzle end, said projection having an inclined surface and accommodated within a recess located on corresponding surface of said slide member when said slide is covering said barrel portion in said first position, said slide as moved by said breech block being forced over said surface of said projection to pivot rapidly upward with respect to said frame and barrel during recoil, said slide, when in said second position, having no surface in contact with said projection; said pivoting motion occuring while a projectile is still traveling in the barrel and furthest away from the muzzle end of said barrel, said motion exerting a downward force on said barrel to tend to hold the firearm in an aimed position.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO. 3,866,516 Dated Februarv 18. 1975 -Inventor(s) Frisoli, David M.

It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

TITLE PAGE after (54) The title incorrectly reads "SEMI-AUTOMATIC PISTON EMPIOYING A PIVOIALLY,SLIDEABLE MEMBER and should read ---SEMIAUI'OMATIC PISTOL EMPIOYING A PIVOIAILY, SLIDEABLE MEMBER--.

COLUMN 1 Title incorrectly reads "SEMI AU'IOMATIC PISTON EMPIOYING A PIVOI'ALLY, SLIDEABLE MEMBER" and should read --SEMIAUTOMATIC PISTOL EMPLOYING A PIVUI'ALLY, SLIDEABLE I IEII IBER-- ---.v

Signed and sealed this 27th day of May 1975.

(SEAL) Attest:

- C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks USCOMM-DC 8037 6-P69 FORM PO-105D (10-69) -& u.s bovznuusm mum-ms OFFiCE: was 0-366-334.

Patent NO- 3,866,516 Dated February 18, 1975 Invent r( Frisoli, David M.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

TITLE PAGE after (54) The. title incorrectly reads SEMI-AUTOMATIC PISTON EMPLOYING A PWUIALLY, SLIDEABLE MEMBER and should read --SEMIAU'I'Q .IATIC PISTOL EMPLOYING A PIVOTALLY, SLIDEABLE MEMBER--.

COLUD N l Title incorrectly reads "SE lI-AU'IOMATIC PISTON ENQ LOYING A PIVOIALLY, SLIDEABLE MEMBER" and should read -SEMI-AUTOMATIC PISTOL EMPIOYING A PIVOI'ALLY, SLIDEABLE MEMBER Signed and sealed this 27th day of May 1975.

(SEAL) Attest:

- C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks FORM F'O-1050 (10-69) USCOMM-DC 60376-P69 k U.S. GOVERNMENT PRINTING OHFECE: Hi9 0-366-334.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US6415701 *Jan 11, 2000Jul 9, 2002Hesco IncorporatedForward mounted breech locking mechanism
US7726229May 30, 2007Jun 1, 2010Crane Tactical LlcRotatable and retractable rear gun sight
US7901399 *Jun 13, 2007Mar 8, 2011Hansen Medical, Inc.Interchangeable surgical instrument
US8065950 *Apr 24, 2008Nov 29, 2011Hans Wrage & Co. GmbhAutomatic pistol
US8303576 *Jan 20, 2011Nov 6, 2012Hansen Medical, Inc.Interchangeable surgical instrument
US8539706 *Jun 13, 2012Sep 24, 2013Thomas J. ViewegRecoil reducing firearm system
US20080033453 *Jun 13, 2007Feb 7, 2008Hansen Medical, Inc.Interchangeable surgical instrument
US20090188147 *May 30, 2007Jul 30, 2009Crane Tactical, Inc.Rotatable and retractable rear gun sight
US20110017058 *Apr 24, 2008Jan 27, 2011Victor Anatolevich KaminskyAutomatic pistol
US20110118756 *Jan 20, 2011May 19, 2011Hansen Medical, Inc.Interchangeable surgical instrument
US20160146558 *Jun 12, 2014May 26, 2016Christian KadaConversion set for a firearm and method for converting a firearm
Classifications
U.S. Classification89/190, 89/198
International ClassificationF41A3/06, F41A3/00, F41A3/32
Cooperative ClassificationF41A3/06, F41A3/32
European ClassificationF41A3/06, F41A3/32