The .45 GAP or .45 Glock (11.43×19mmRB) is a pistol cartridge designed by Ernest Durham, an engineer with CCI/Speer, at the request of firearms manufacturer Glock to provide a cartridge that would equal the power of the .45 ACP, have a stronger case head to reduce the possibility of case neck blowouts, and be shorter to fit in a more compact handgun. The .45 GAP is the first commercially introduced cartridge that has been identified with Glock.

Glock Ges.m.b.H. is a light weapons manufacturer headquartered in Deutsch-Wagram, Austria, named after its founder, Gaston Glock. The company makes popular polymer-framed pistols, but also produces field knives, entrenching tools, various horse related products, and apparel.