Center pin lock for single-action revolver

A single-action revolver is disclosed which includes a cylinder frame and a cylinder to be mounted in the cylinder frame and a barrel removably connected to the cylinder frame. A center pin extends through the cylinder frame for rotatably mounting the cylinder within the cylinder frame, and a release plunger is provided for retaining the center pin in engagement with the cylinder frame in a conventional manner. The improvement is directed to interlocking means for retaining the center pin in engagement with the cylinder frame and includes a slot formed in the barrel and a collar formed on the center pin for engagement with the barrel slot to prevent release of the center pin. In addition, the center pin includes an additional notch for receiving the release plunger when the collar is rotated into engagement with the barrel slot. In this manner, the interlocking means prevent the center pin from being jolted loose during firing of the revolver.

FIELD OF THE INVENTION 
The present invention relates generally to single-action revolvers and 
specifically to an improved locking mechanism for the center pin on which 
the cylinder is rotatably mounted to prevent the center pin from being 
jolted loose during firing of the revolver. 
BACKGROUND OF THE INVENTION 
Single-action revolvers typically include a cylinder rotatably mounted on a 
center pin. For many years, the cylinder frame of the coventional 
single-action revolver has included a spring-biased release plunger for 
maintaining the center pin in engagement with the cylinder frame and 
cylinder. 
However, the release plunger has not been completely satisfactory in 
maintaining the center pin in proper position during repeated firing of 
the revolver. It has been experienced that after repeated firing of the 
revolver, the repeated recoil action causes the spring of the release 
plunger to be compressed and thereby release the center pin from 
engagement with the cylinder frame. This problem may partially be avoided 
if the notch of the center pin which the release plunger engages was made 
slightly deeper. However, this would create the additional problem of 
substantially weakening the center pin and is therefore not an acceptable 
solution to the problem. 
Broadly, it is an object of the present invention to provide an improved 
locking mechanism which overcomes the aforesaid problem. Specifically, it 
is within the contemplation of the present invention to provide an 
interlocking mechanism which interlocks the center pin with the barrel in 
a positive manner to prevent the center pin from being jolted out of 
proper position during repeated firing and recoil of the revolver. 
It is a further object of the present invention to provide a double-locking 
mechanism for the center pin so that when one locking mechanism is in 
engagement with the barrel, the release plunger is in engagement with a 
notch which has been added to the center pin to form a second locking 
mechanism which operates to prevent rotation of the center pin when the 
cylinder is rotated or when the revolver is fired. 
SUMMARY OF THE INVENTION 
Briefly, in accordance with the principles of the present invention, an 
improved locking mechanism for the center pin of a single-action revolver 
is provided. The revolver includes a cylinder rotatably mounted on the 
center pin. In a conventional manner, the spring-biased release plunger of 
the cylinder frame engages a notch formed in the center pin to prevent 
rotation of the center pin when the cylinder is rotated. Although this 
release plunger has been employed in the past to maintain the center pin 
from being axially moved out of position, this has not been completely 
satisfactory. 
Accordingly, in order to prevent the center pin from being axially jolted 
out of position during repeated firing of the revolver, an improved 
interlocking mechanism is provided which includes a slot formed in the 
barrel and a collar formed on the center pin for engagement with the 
barrel slot. The engagement of the collar and barrel slot acts as a lock 
or stop to prevent axial movement of the center pin relative to the 
cylinder frame and barrel. The collar of the center pin is moved into and 
out of engagement with the barrel slot by rotating the center pin 
180.degree.. As a result, the release plunger is moved out of engagement 
with the conventional notch of the center pin when the center pin is 
rotated 180.degree.. Accordingly, a second notch has been formed in the 
center pin for engaging the release plunger when the collar is rotated 
into engagement with the barrel slot. Preferably, the notches are formed 
in the surface of the center pin approximately 180.degree. apart from each 
other. 
Advantageously, as a result of the present invention, a double-locking 
mechanism is provided for removably retaining the center pin in proper 
engagement with the cylinder and cylinder frame. The rotation of the 
collar into engagement with the barrel slot provides a positive locking 
mechanism to prevent axial movement of the center pin. In addition, by 
providing a second notch in the center pin, it is brought into engagement 
with the conventional release plunger and provides a second locking 
mechanism for preventing rotation of the center pin, especially when the 
cylinder is rotated. In this manner, as the release plunger and notch 
prevent rotation of the center pin, the collar of the center pin cannot be 
rotated out of engagement with the barrel slot. Accordingly, the two 
locking mechanisms cooperate with each other to prevent axial or 
rotational movement of the center pin during repeated firing and recoil of 
the revolver.

DETAILED DISCUSSION OF PREFERRED EMBODIMENT OF THE INVENTION 
Referring now to FIG. 1, there is shown the improved single-action revolver 
of the present invention, generally designated by the reference numeral 
10, which includes the following conventional components: a handle grip 
and frame 12 connected to a cylinder frame 14; a hammer assembly 16; a 
trigger assembly 18; a cylinder 20 rotatably mounted on center pin 22 
within cylinder frame 14; a barrel 24 threadedly connected to cylinder 
frame 14; an ejector housing 26 on barrel 24; and a center pin release 
plunger 28 mounted on cylinder frame 14 for engagement within a notch 30 
formed in the surface of center pin 22. As shown in greater detail in FIG. 
3, the release plunger 28 is spring biased by spring 31 so that when 
center pin 22 is pushed all the way into its proper position within 
cylinder 20, the plunger 28 can move relative to notch 30, and the plunger 
is forced to do so by spring 31. The foregoing elements and their 
cooperative working relationship are well known in the art and need not be 
described in further detail for an understanding of the present invention. 
Referring to FIG. 4, the conventional prior art center pin 22' is shown. As 
explained above, the conventional prior art center pin 22' included a 
notch 30' for engaging the release plunger 28. In addition, a collar 32' 
was formed on the center pin and included a cutaway area 32a' which 
matched the circular periphery of the barrel 24 for engagement with the 
underside of the barrel while plunger 28 was in engagement with depression 
30'. 
In order to provide the improved locking arrangement of the present 
invention, the center pin 22 has been modified, as shown in FIG. 3. The 
center pin 22 not only includes notch 30 but, in accordance with the 
present invention, is provided with a second notch 34 for engaging plunger 
28 when center pin 22 and collar 32 are rotated into the locking position, 
in manner to be explained. Also, in accordance with the present invention, 
cutaway area 32a has been designed so that surface 32a is now 
substantially flattened. In addition, in order to rotate center pin 22, a 
receiving slot 36 for a screwdriver has been formed in the end of center 
pin 22. Of course, any other suitable means for rotating the center pin 
and collar into locking position can be provided. For example, the area 
22a of the center pin could be knurled. Finally, in accordance with the 
present invention, a slot 38 has been formed in the bottom half of barrel 
24 adjacent the end of the barrel which engages the cylinder frame 14, 
which slot 38 is clearly shown in FIGS. 1 and 2. 
In order to operate the improved center pin lock of the present invention, 
center pin 22 is inserted through cylinder frame 14 and into cylinder 20 
in the conventional manner. As a result, release plunger 28 cooperates 
with notch 30, also in the conventional manner. Then, center pin 22 is 
rotated approximately 180.degree. by any suitable means, such as by a 
screwdriver inserted into slot 36 of the center pin. As a result, the 
substantially flat side 32a of collar 32 will be rotated away from barrel 
24, and the enlarged portion 32b of collar 32 will be rotated into 
engagement with barrel slot 38. As a result, collar portion 32b in 
cooperative engagement with barrel slot 38 acts as a positive stop or lock 
to prevent axial movement of the center pin 22 out of engagement with 
cylinder frame 14 and cylinder 20. In addition, when center pin 22 is 
rotated 180.degree., the second notch 34 is brought into working 
engagement with release plunger 28. As a result, the cooperation of notch 
34 and plunger 28 prevents rotation of the center pin 22 when the cylinder 
20 is rotated and also when the revolver is fired. Thus, collar portion 
32b of center pin 22 cannot be rotated out of engagement with barrel slot 
38. Accordingly, it will be understood that as notch 34 and plunger 28 
prevent rotation of the center pin, and as collar portion 32b and barrel 
slot 38 prevent axial movement of center pin 22, both of these locking 
mechanisms cooperate to prevent release of the center pin from proper 
engagement with cylinder frame 14 and cylinder 20. 
A latitude of modification, change, and substitution is intended in the 
foregoing disclosure, and in some instances, some features of the 
invention will be employed without a corresponding use of other features. 
Accordingly, it is appropriate that the appended claims be construed 
broadly and in a manner consistent with the spirit and scope of the 
invention herein.