By Jerry Tarble
A former associate of Gene Stoner told me that he had two uncommon qualities which were seldom possessed by the same individual. He said Mr. Stoner was both a genius and a gentleman. In the very limited time I spent with Mr. Stoner, it was immediately evident that he was indeed a true gentleman. When I first met him, I was intimidated, just by being in his presence. It did not take long, however, for he and his wife, Barbara, to quickly put me at ease. His Stoner 63 system, considered by me to be his ultimate design, shows that the term genius is not a misnomer.
I find the most intriguing design detail of the Stoner 63 system to be that the rifle and carbine configurations fire from the closed -bolt position, while the automatic rifle, light machine gun, medium machine gun, and fixed machine gun configurations fire from the open-bolt position. How is this accomplished without unnecessary complexity?
Gene Stoner managed to perform this feat using two interacting parts, the firing pin and a special collar contained within the bolt carrier. (Fig. 1) The bolt carrier of the Stoner 63 holds this collar (painted white for identification). It is fixed by means of a snap ring to the front, and a stack of Belleville spring washers to the rear. This stack of spring washers is also the buffer assembly. (Fig. 2) This special collar has a D shaped hole in the collar. At the rear of this flat are two steps, one slightly forward of the other. The firing pin base also has a corresponding flat which engages in the bolt carrier cap. This base can be rotated to either of two spring-fixed positions. (Fig. 5 & 6)
In the closed bolt position the bolt carrier cap is rotated so the timer trip is pointing away from the operating rod. (Fig. 7) This orients the firing pin in relation to the “D” collar so the forward step of the flat is aligned parallel to the flat side of the “D”. (Fig. 8) This allows the firing pin to float and ignite the cartridge primer when the firing pin is struck by the hammer.
To switch to the open bolt firing mode, the magazine catch, timer, and hammer are removed from the trigger housing assembly. (Fig. 9) Then, the bolt carrier cap is simply rotated 180 degrees so the timer trip is pointed toward the operating rod. (Fig. 10) This positions the face of the rear firing pin step in front of the flat side of the “D” shaped hole in the collar. (Fig. 11) The firing pin is now held fixed in this forward position. When the bolt locks into the barrel extensions, the fixed firing pin protrudes through the face of the bolt and strikes the primer of the cartridge.
Gene Stoner’s design then gives us a fixed or floating firing pin with the turn of a switch. (Fig. 12) Adding or deleting three parts in the trigger housing assembly completes the transition from closed -bolt or open- bolt firing. Remember, this design was conceived and executed in 1962, before the advent of modern computers and CAD/CAM programs. It merely required genius.
Fig. 12 Top: Stoner 63 operating rod/bolt assembly. Bolt carrier cap is positioned for closed bolt operation.. Note protrusion of firing pin base from rear of bolt carrier cap.Bottom: Stoner 63 operating rod/bolt assembly. Bolt carrier cap is positioned for open bolt operation. Note lack of firing pin base protrusion from rear of bolt carrier cap.
|This article first appeared in Small Arms Review V1N4 (January 1998)|