a 9×19mm semi-automatic pistol designed and built by Grand Power s.r.o. in Slovenská Ľupča.The K100 uses a rare locking system, similar in some ways to the Beretta Cougar, Px4 Storm, and Brügger & Thomet MP9 which employs a rotating barrel lock, which in the K100's case is cammed by a cross pin. When the pistol is fired the barrel and slide move backward together for about 3/8 of an inch while the barrel is cammed clockwise (with respect to the shooter) by a flat, twisting, helical "cut" in the barrel extension.The standard K100 has a barrel length of 108 mm (4.3 in) and operates in both single- and double-action mode. The hammer must be manually decocked for carry in double-action mode with a chambered round. The safety can be applied with the hammer cocked, but can not be applied with the hammer in the forward position. The safety does not lock the slide. A decocking hammer group is available as an option on many models.