Thus, engaging the safety simultaneously reduced tension on the firing pin spring. A hammer block is similar to a firing pin block. It also provided a mounting for the firing pin. There is an additional internal safety that acts as a firing pin block. The Custom II has an internal firing pin safety. The m/45 is an open bolt design with a fixed firing pin. There is an inertia type firing pin design&colon;. The hammer and firing pin was mounted on an arm. Most variants of the M1911 pistol use this type of firing pin. Their firing pin holes are welded closed on the bolt face. Other safety features include a firing pin block which mechanically obstructs the firing pin. The lever hit the bullet on the nose, driving it into the firing pin. Several companies have developed a firing pin block safety. A firing pin strikes the primer and ignites it. The complete cycle action also resets the firing pin.