The J. Kimball Arms Company of Detroit introduced a semiauto pistol in 1955, chambered for the .30 Carbine cartridge - what better companion for the tactical uber weapon of the day, the M1 Carbine? Kimball’s pistol was styled heavily after the High Standard, and it looks good and handles well. The .30 Carbine cartridge is too powerful for a blowback pistol, however, and so Kimball needed some type of locked breech or delaying mechanism. He chose to cut an annular ring in the front of the chamber - the mouth of the brass would expand into this ring upon firing, and the force required to press it back down to the diameter of the chamber body would force the slide to remain closed long enough for pressure to drop to a safe level.
However, the system was not adequate for the cartridge. The slide velocity was high enough that the guns very quickly battered the slide stop block. The would peen and deform at first, then crack, and eventually either bend to the point that the gun would not cycle, or break off and allow the slide to come right off the back of the frame. I can’t find any documentation of anyone actually injured in this way, but that was obviously the concern. Only between 250 and 300 of the pistols were made before the company went bankrupt and closed. There had been plans to expand the line to include gun in .38 Special, .357 Magnum, and .22 Hornet, but none of those went any farther than prototypes.
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