position often have a fixed firing pin that protrudes from the face of the bolt. As the bolt fully closes on the breech the primer of the newly chambered round is struck, causing the cartridge to fire. The Owen and F1 submachine gun are examples that use bolt-face fixed firing-pins. Some mortars use a fixed firing pin mounted in the breech plug. When a mortar round is dropped down the barrel, a primer in the base of the mortar round strikes the firing pin and ignites the propelling charge. Floating firing pins In firearms terminology, a floating firing pin is one which is unrestricted by a firing-pin return spring or similar. While it will be captive and unable to simply fall out, either forward or backward, it is otherwise free to slide within these stops. The trapdoor Springfield Model 1865 is an example of a floating firing pin. Striker Hammer-operated firing mechanisms use a relatively light firing pin and rely on a transfer of momentum received from a spring-loaded hammer, in the same fashion as a punch or chisel relays the blow from a mallet. In firearms terminology, a striker (or striker mechanism) derives the impact force to strike the primer from a spring acting directly upon the 'firing pin' - similar to a crossbow, where the striker (firing pin) is like the crossbow bolt (arrow). A striker mechanism is very common in bolt action firearms but not to the exclusion of a hammer-operated mechanisms. It will also be found in other actions where the breechblock reciprocates directly inline with the axis of the barrel. A striker mechanism will consist of the striker spring (firing spring) and the striker. The striker spring is a relatively strong spring sufficient to initiate firing. A typical striker consists of a narrow striking point, a heavier section that acts as a spring guide for the striker spring, a shoulder to restrain the spring, and a catch piece which is engaged by the trigger sear to hold the spring under tension when "cocked" and ready to fire. The striker spring is compressed between the striker's shoulder and the rear of the breechblock. A striker may be assembled from several component; however, the stored energy in the striker spring is transferred directly to the striker and then to the primer without any intermediate transfer of energy or momentum. As striker mechanisms combine both functions of hammer