This one is blowback, but sort of delayed, the Kimball pistol, in .30 Carbine, and the one-off select-fire variant to boot.
While there's no rollers, levers, or gas ports for delaying this slide, what the Kimball does is that it has an annular ring machined into its chamber, which the brass casing expands into as the case is fired, which is then forced to be straightened out as pressure pushes back against the breech.
Virtually the opposite of the lateral flutes in the chamber of a G3 rifle, this concept has previously been used in the Fritz-Mann pistol, a little .25 Auto pocket piece, but even with that little cartridge it tends to spit out bulged cases. The Kimball pistols meanwhile were widely described as terrifying to shoot, urban legend states that the slide came loose and lodged itself into someone's eyesocket, but that's almost certainly just someone's imagination.
Most successfully, this concept was used for the FG-42 by Louis Stange, a rifle/LMG using a long-stroke gas piston and rotating bolt, the chamber's profile intentionally not being shaped after the taper of 7.92mm Mauser, making the casing and its shoulder expand into that space. The entire point was really just for increasing margins to allow for weight savings elsewhere.
>>64127398
Isn't that because some source somewhere claimed it was as low as 70db, even though that wasn't really correct, but people have just repeated it?
