US 3657959 A
The invention provides a conversion means for converting a large caliber automatic pistol to an accurate sub-caliber automatic pistol without making any exterior changes in the large caliber pistol. In the prior art the well-known Colt automatic pistol, caliber .45, Government model, can be converted to a sub-caliber automatic pistol by means of a conversion kit which includes a different slide, a different barrel, a different recoil spring, a different slide-stop, and a series of spacers to surround the recoil spring guide to shorten the recoil movement. To improve the accuracy of such converter large caliber automatic pistol the present invention makes the following changes in certain of the conversion parts.
Description (OCR text may contain errors)
[4 1 Apr. 25, 1972  AUTOMATIC PISTOL AND SUB- CALIBER CONVERSION THEREFOR Frederick H. Kart, RD. 2, Box 929, Riverhead, N.Y. 11901  Filed: Aug. 14, 1969  Appl.No.: 849,977
Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Stephen C. Bentley Attorney-Howard .1. Churchill, Robert S. Dunham, P. E. Henninger, Lester W. Clark, Gerald W. Griffin, Thomas P. Moran and R. Bradlee Boal  ABSTRACT The invention provides a conversion means for converting a large caliber automatic pistol to an accurate sub-caliber automatic pistol without making any exterior changes in the large caliber pistol. in the prior art the well-known Colt automatic pistol, caliber .45, Government model, can be converted to a sub-caliber automatic pistol by means of a conversion kit which includes a different slide, a different barrel, a different recoil spring, a different slide-stop, and a series of spacers to surround the recoil spring guide to shorten the recoil movement. To improve the accuracy of such converter large caliber automatic pistol the present invention makes the following changes in certain of the conversion parts.
The smaller caliber barrel is provided at its rearward end with aligned checks for engagement with the upper surface of the receiver; a flattened surface is provided on one lateral face of such smaller caliber barrel including one of said cheeks to facilitate insertion of such barrel within the pistol slide; an elongated hole inclined upwardly at an angle of 45 is provided in the barrel extension member which receives the slidestop pin; a screw-threaded hole is provided in the front face of the barrel extension member for receiving a barrel locking screw which extends through the recoil spring guide; the barrel locking screw engages the front end of the recoil spring guide and upon tightening of said screw brings the barrel cheeks and upper surface of the receiver into firm engagement; and the slide stop is provided with a relatively movable bar and pin.
5 Claims, 8 Drawing Figures PATENTED APR 2 5 1972 SHEET 18F 2 Tic. l.(PRloR ART) Tia E (PRlOR ART) INVENTOR. FRmm/ck H, K
PATENTEDAPMS m2 3.657, 959 SHEET 2 [IF 2 I NVENTOR. fkfpse/c/z H K427 ATTO AUTOMATIC PISTOL AND SUB-CALIBER CONVERSION THEREFOR This invention relates to automatic pistols. More particularly it provides improved means for converting automatic pistolsof large caliber'to sub-caliber while maintaining the accuracy of the pistol.
The Colt automatic pistol, caliber .45, Government model, is well known in the art-and has been extensively used as a service pistol.
It has been proposed in the past to convert such Colt .45 caliber automatic pistol to a sub-caliber pistol, such for instance as a .22 caliber pistol, by the use of a conversion kit which included various parts to be substituted for parts of the .45 caliber pistol inorder to convert it to a .22 caliber pistol. One such conversion kit as offered for sale by the manufacturer of the Colt .45 caliber pistol includes a different slide, a different barrel, a different recoil spring, a different slide-stop, and a series of spacers to surround the recoil spring guide to shorten the recoil movement.
lnconverting a .45 caliber piston to a .22 caliber pistol, it is of course highly desirable that the changes made in the .45 caliber pistol not be permanent. On the contrary, it is highly desirable that the .22 caliber conversion be readily restorable to its original condition as a .45 caliber pistol.
Furthermore, in competitive target shooting, such as in hard ball matches, it is a basic requirement that there shall have been no exterior changes in the .45 caliber pistol.
I have found that with prior art conversion kits in changing a .45 caliber pistol to a sub-caliber pistol such as a .22 caliber pistol, it has not been possible to attain a high degree of accuracy with such sub-caliber pistol. Hence, up until now, in order to attain the desired accuracy with a .45 caliber pistol, when converting. it to a .22 caliber pistol, it has been a common practice to utilize, on an individual basis, the services of a skilled gunsmith who would carefully adjust and modify the various tolerances so as to impart as much accuracy as possible to such converted pistol. After such conversion, however, it was not possible to restore the pistol to its original .45 caliber condition.
It is an object of the present invention to provide apparatus for converting a .45 caliber pistol to a sub-caliber pistol such as a .22 caliber without modifying the exterior appearance of such pistol; to permit such pistol to be returned very quickly to its original .45 caliber condition; and to impart to such .22 conversion a high degree of accuracy such that it is at least as accurate, if not more accurate than a .45 caliber pistol which has been modified individually by a gunsmith for use in competitive target shooting.
In accomplishing the foregoing objects I start with a .45 caliber Colt pistol which has been modified with the manufacturers conversion kit to a .22 caliber pistol. I then modify the .22 caliber pistol which results from such conversion by providing on the substitute .22 caliber barrel at its rearward end two longitudinally-disposed aligned checks which are brought into firm engagement with the upper surface of the pistol receiver, and thereby assure pistol accuracy independently of the tolerances between the slide and receiver. 1 also provide on one of the lateral faces of the conversion barrel a flat portion which permits such modified conversion barrel to be inserted in the slide from the bottom.
In addition, I also provide an upwardly inclined elongated slide-stop hole in the downwardly projecting extension member on the barrel and also provide a tapped or screwthreaded hole in the front end of such extension member which is in alignment with the recoil spring guide, such screwthreaded hole being in communication with the upwardly-inclined, elongated slide-stop hole, and a barrel locking screw extending through such recoil spring guide and into such screwth'readed hole in the front end of the barrel member with the head of said screw bearing against the recoil spring guide, which in turn bears against the receiver, whereby upon tightening of the screw the barrel is pulled forwardly, the slide-stop pin rides upwardly along the elongated slide-stop hole, the barrel is forced downwardly, and the aligning cheeks are brought into firm contact with the receiver. I have also provided an improved slide-stop which permits the slide-stop bar to turn on the pin.
For a more detailed understanding of the invention reference will now be made to the accompanying drawings wherein:
FIG. 1 is a side elevation, partially fragmentary and partially broken away to show underlying structure, of the prior art Colt .45 caliber automatic pistol, Government model, converted by the well-known conversion kit to a .22 caliber automatic pistol.
FIG. 2 is a fragmentary perspective view of the slide-stop for such prior art .45 caliber Colt, Government model, pistol, converted to a .22 caliber pistol.
FIG. 3 is a view similar to FIG. 1 but showing a .45 caliber Colt pistol converted according to the prior art to a .22 caliber pistol and then further modified according to the present invention.
FIG. 4 is a view similar to FIG. 2 but showing the slide-stop as modified according to the present invention.
FIG. 5 is a sectional view taken on the line 5-5 of FIG. 1 looking in the direction of the arrows and showing the slide, barrel, receiver and slide-stop of the prior art Colt .45, Government model, pistol, converted according to the prior art to a .22 caliber pistol.
FIG. 6 is a view similar to FIG. 5 but showing the modified barrel, slide-stop, and barrel locking screw provided by the present invention.
FIG. 7 is an enlarged fragmentary view in side elevation similar to FIG. 3, showing one side of the barrel as modified according to the present invention.
FIG. 8 is an end elevational view of the barrel viewed from the right of FIG. 7.
It will be noted that for clarity of disclosure and ready reference, FIGS. 1, 2 and 5 carry the legend Prior Art in parentheses.
. Referring now to the drawings for a more complete understanding of the improvements made by the present invention, it will first be noted from FIG. 1 of the drawings, which illustrates the well-known Colt automatic pistol, caliber .45, Government model, converted according to the prior art to a .22 caliber pistol, that such pistol includes the basic elements of: A receiver 10 having a grip portion 11, a trigger 12, a safety 13, a recoil spring guide 14, spacers 14a surrounding said spring guide, a recoil spring 15 surrounding such guide and engaging said spacers, barrel 16 from which the bullet is ejected, and a slide 17 disposed over such barrel and in sliding engagement with the receiver. Such prior art converted Colt pistol also includes a slide-stop 20, such as shown in perspective in FIG. 2 of the drawings, including a bar 21 and a pin 22 rigidly connected thereto. The pin 22 of the slide-stop is also shown in crosssection in FIG. 1.
With the converted pistol of the prior art, for accuracy of firing it has been necessary to maintain very close and accurate tolerances between the barrel 16, the slide 17 and the receiver 10. Thus, as best seen in FIG. 5 of the drawings, which is a sectional view taken along the lines 5-5 of FIG. 1, the .22 caliber Colt conversion slide has longitudinal grooves 23 which are interfitted with and engaged by longitudinal flanges 24 on the Colt .45 caliber receiver, and that such slide also has longitudinal flanges 25 which are interfitted with and engaged by longitudinal grooves 26 on the receiver. Such interfitted grooves and flanges must be accurately machined to provide the maximum of pistol accuracy.
It will thus be understood as shown in FIG. 5 of the drawings that the accuracy of a Colt .45 and its conversion .22 caliber pistol is dependent upon the closeness of tolerances between the barrel and the slide and the tolerances between the flanges and grooves in the slide and receiver.
It will also be noted in FIG. 2 of the drawings that in the prior art Colt conversion pistol the slide-stop 20 has the pin 22 rigidly secured to the bar 21.
In modifying a conversion pistol of the type shown in FIG. 1 to a .22 caliber pistol according to the present invention, a .22 caliber barrel 27 is substituted for the barrel 16. This barrel is illustrated in FIGS. 3, 6, 7 and 8 of the drawings. It will first be noted from FIG. 6 that such barrel has been provided on one side with a flat surface 28 which permits the barrel to be inserted through the bottom of the slide 17. The receiver 10 is the same as the receiver shown in FIGS. 1 and and has not been changed or altered.
The barrel 27 has been provided on each side with cheeks 30, 30a at the rear of the barrel and which are integral therewith, such cheeks being accurately ground to provide guiding edges 31 which bear against and firmly engage the upper surfaces 32 of the receiver 10. With this construction it will be noted that the accuracy of the pistol is no longer dependent upon the tolerances between flanges and grooves on the slide 17 and the receiver but instead the accuracy is directly controlled by the engagement of the cheeks 30 on the barrel 27 with the upper surfaces 32 of the receiver. In practice it has been found that such cheeks preferably have a longitudinal dimension along the barrel of approximately 1 inch.
The second change or alteration made by the present invention is that a hole is provided in the front face of barrel extension member 35, such hole being marked 36. The hole 36 is in axial alignment with the spring guide 14. A barrel locking screw 37 is inserted within the spring guide and engages screwthreadedly in the hole 36 in barrel extension member 35.
As with the prior art conversion, a plurality of spacers 40 surround the spring guide and shorten the effective length of the recoil spring, the end coil of the spring engaging the exposed face of the outermost spacer, the spacers usually being about three-sixteenths inch thick. I have found that five or six of such spacers provide the proper timing for firing a .22 caliber cartridge while permitting the slide to work in a long enough stroke that the disconnector and other parts function in proper sequence. Generally speaking, the prime purpose of the spacers is to correct the timing for a .22 caliber bullet as against a .45 caliber bullet.
A further change which is made by the present invention is that the hole 41 for the pin 22 of the slide-stop in the pistol of FIG. I has been elongated along a 45 axis to provide hole 41 as best seen in FIG. 7. It will also be noted, as best seen in FIG. 4, that the slide stop 45 of the present invention as shown in exploded view in FIG. 4, does not have its pin and bar integral or rigid one with the other, but on the contrary a through hole 46 is provided in the bar 47 for receiving a reduced end connection 48 for the pin 49. A screw 50 for engagement in the internally screwthreaded end 48 holds the pin and bar in assembled relation while permitting such bar and pin to pivot or rotate relatively to each other.
By reference to FIG. 3, it will be noted that the barrel locking screw 37 bears against the front end of the recoil spring guide 14, and is engaged in the screwthreaded hole 36 in the front end of the barrel extension member 35, a clearance 51 being provided. The opposite end of the spring guide, in turn, bears against the receiver 10. Upon tightening of the screw 37 the barrel 27 is pulled forwardly, the slide-stop pin 49 is caused to ride upwardly along the elongated slidestop hole 41 the barrel 27 is forced downwardly and the aligning cheeks 30, 30a are brought into firm contact with the upper surface 32 of the receiver 10. In this way the cheeks on the barrel of the .22 caliber pistol align directly with the upper surface of the receiver and it is not necessary to rely upon the tolerances between the receiver and slide for accuracy.
From the foregoing description it will be understood that I have provided improved means for converting a .45 caliber pistol to a .22 caliber pistol without making any permanent changes in such .45 caliber pistol and without any exterior changes which would prevent such pistol from being used in competitive hard ball" matches. It will also be apparent that the .22 conversion can be readily reconstituted as a .45 caliber istol. p It will thus be apparent that an owner of a .45 caliber pistol who is interested in competitive target shooting can readily change such a pistol into an accurate .22 caliber target pistol merely by following the teachings of the present invention.
What I claim is:
1. An automatic pistol having a receiver, a slide, a barrel for recoiling movement relative to said receiver and slide, spring means yieldingly resisting said recoiling movement, said receiver and slide having interfitting grooves and flanges, said receiver having an upper surface above said interfitting grooves and flanges on each side of said barrel which parallels the axis of said barrel, and conversion means for converting said pistol from a large caliber bore to a smaller caliber bore, characterized in that said conversion means comprise a. a small caliber bore barrel having on each exterior side wall adjacent its rearward end a cheek extending forwardly from said rearward end, parallel to the axis of said barrel, each cheek having a lower surface adapted for engagement with one of said upper surfaces of said receiver, and
b. means for firmly engaging said cheeks and the upper surfaces of said receiver at all times.
2. An automatic pistol according to claim 1, wherein said small caliber bore barrel has one of its lateral faces including one of said cheeks flattened so as to permit said small caliber bore barrel to be inserted in the slide from its underside.
3. An automatic pistol according to claim 1, in which the barrel has a downwardly projecting extension member, a recoil spring guide, a coil spring surrounding said guide, and a plurality of spacers surrounding said spring guide adjacent said extension member and serving to limit the recoil movement of the slide to accommodate to a smaller caliber bullet, further characterized in that said conversion means also comprise c. a screwthreaded hole in the front face of said barrel extension member,
d. a barrel locking screw disposed within said spring guide and having a head engaging the front end of said spring guide, said screw being in threaded engagement with the hole in the front face of said barrel extension member, and
e. a slide-stop pin disposed in an elongated, upwardlyinclined slot in said barrel extension member,
whereby upon tightening of said barrel locking screw the cheeks on the conversion barrel are forced into firm engagement with the upper surface of the receiver.
4. An automatic pistol according to claim 3, wherein f. the elongated, upwardly-inclined slot is disposed at an angle of approximately 45 to the longitudinal axis of the barrel, and
g. the slide-stop has a relatively movable bar and pin with the pin mounted in the elongated, upwardly-inclined slot.
5. An automatic pistol according to claim 4, wherein the slide-stop comprises a pin member with a reduced end having a screwthreaded hole therein, a bar having a bearing hole at one end for receiving the reduced end of the pin, and a screw for engagement through the hole in the bar with the screwthreaded hole in the pin, whereby relative movement between the pin and bar is permitted.