Kel-Tec PR57

The weapon is chambered in the FN 5.7x28mm round, uses a rotating barrel locking operation and most unusually, uses a 20 round internal magazine fed from stripper clips (similar to the Steyr M1912 and the Grendel P10 .380).

The hammer rides at approximately the half-cock position, and the relatively long trigger pull moves the hammer to full-cock, then releases the hammer to strike the firing pin. There is a false reset on releasing the trigger; the actual reset is all the way at the front of trigger travel. The sights are fixed, albeit the front sight is held in place with a screw, and the rear sight is molded into the plastic rear slide cover. The rear of the slide is drilled and tapped for a rear optic plate, which comes in the box from the manufacturer.

Manufacture of the barrel and slide use a number of machining steps on a lathe, unusual for a slide, followed by more conventional mill work for final finishing. This likely lowers the manufacturing cost of the arm. Two small guide rods and captive recoil springs are mounted underneath the rotating barrel. The pistol is very easy to field strip by unusually pushing the trigger forward.

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