Firearm systems and methods for accommodating different bullet casing lengths

A firearm, comprising

• a frame assembly;
• a slide assembly releasably and slidably coupled to the frame assembly;
• a bolt assembly including a leading surface;
• a firing pin;
• and
• an adjuster comprising:
• a body defining a first bore, defining a leading surface, and having a thickness, wherein the leading surface of the body of the adjuster is configured to interface with a rear portion of a first cartridge and a rear portion of a second cartridge, wherein the body spaces the leading surface of the body of the adjuster from the leading surface of the bolt assembly, and wherein the body has an outer periphery that is smaller than a diameter of the first cartridge and the second cartridge such that the body is protrusible into a chamber of a barrel to interchangeably fully seat the first cartridge having a first length and the second cartridge having a second length, the second length of the second cartridge longer than the first length of the first cartridge;
• and
• an extension coupling the body to the bolt assembly, the extension defining a second bore that shares a common central axis with the first bore, wherein the first bore and the second bore receive the firing pin such that the firing pin at least selectively protrudes from the leading surface of the body of the adjuster to engage the first cartridge and the second cartridge.