The .45 GAP (Glock Auto Pistol) or .45 Glock (11.43×19mmRB) is a

pistol A pistol is a type of handgun, characterised by a gun barrel, barrel with an integral chamber (firearms), chamber. The word "pistol" derives from the Middle French ''pistolet'' (), meaning a small gun or knife, and first appeared in the Englis ...

cartridge designed by Ernest Durham, an engineer with CCI/Speer, at the request of

firearm A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and operated by an individual. The term is legally defined further in different countries (see legal definitions). The first firearms originate ...

s manufacturer

Glock Glock (; stylized as GLOCK) is a brand of polymer- framed, short-recoil-operated, striker-fired, locked-breech semi-automatic pistols designed and produced by Austrian manufacturer Glock Ges.m.b.H. The firearm entered Austrian military an ...

to provide a cartridge that would equal the power of the

.45 ACP The .45 ACP ( Automatic Colt Pistol), also known as .45 Auto, .45 Automatic, or 11.43×23mm is a rimless straight-walled handgun cartridge designed by John Moses Browning in 1904, for use in his prototype Colt semi-automatic pistol. After su ...

, 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.

Development

The .45 GAP has the same diameter as the

pistol cartridge but is slightly shorter, and uses a small-pistol primer instead of the large-pistol primer most commonly used in .45 ACP ammunition. Originally, the maximum bullet weight of the .45 GAP was . In order to provide terminal ballistics that matched the standard .45 ACP loads, the .45 GAP was designed to operate at a higher standard pressure—roughly equivalent to the higher pressures found in .45 ACP "+P" rounds. Since the .45 GAP has a much smaller cartridge volume than the .45 ACP, the desired pressure and resulting velocity needed to be achieved through powder selection alone. Later development concluded that the .45 GAP can also fire projectiles, as does the .45 ACP; though this pushes the .45 GAP cartridge to its limits.

Glock .45 GAP pistols

The full-size Glock 37 pistol was introduced by Glock to use the .45 GAP cartridge and was followed by the compact Glock 38 and the subcompact Glock 39. Glock's .45 GAP–sized pistols use the same frame as their 9×19mm/.40 S&W/.357 SIG line of pistols. The slide is slightly wider to accommodate the larger diameter .45 round and is flush with the frame. Magazines for the .45 GAP are of the same dimensions as those of the 9×19mm/.40 S&W/.357 SIG line of pistols.

Other .45 GAP firearms

Initially, due to its acceptance by law enforcement and the popularity of subcompact handguns for

concealed carry Concealed carry, or carrying a concealed weapon (CCW), is the practice of carrying a weapon (usually a sidearm such as a handgun), either in proximity to or on one's person or in public places in a manner that hides or conceals the weapon's pre ...

, a small number of manufacturers decided to produce pistols that were chambered in .45 GAP, but they no longer produce any pistols in that caliber. Only Glock continues to manufacture pistols in the .45 GAP cartridge.

Springfield Armory, Inc. Springfield Armory, Inc., is an American commercial firearms manufacturer and importer based in Geneseo, Illinois. Founded in 1974 by Bob Reese and family, the company produces rifles such as the M1A and imports handguns such as the XD series ...

did make the XD series in .45 GAP, and indeed it was the first commercially available pistol for it, but discontinued that chambering soon thereafter.

Law enforcement applications

Modern law enforcement as a whole has moved away from .45 caliber weapons in favor of firearms chambered in .40 S&W and 9×19mm. Despite this change, the .45 GAP has had a following amongst many law enforcement departments. Three state law enforcement agencies have adopted the .45 GAP as a replacement for their current issue 9×19mm Parabellum (New York) or .40 S&W service handguns (South Carolina and Florida). The

New York State Police The New York State Police (NYSP) is the state police of the U.S. state of New York; it is part of the New York State Executive Department and employs over 5,000 sworn state troopers and 711 non-sworn members. The New York State Police are re ...

(New York Police have recently completed the transition to .45 ACP for their duty round), South Carolina Highway Patrol, and

Florida Highway Patrol The Florida Highway Patrol (FHP) is a division of the Florida Department of Highway Safety and Motor Vehicles. It is Florida's highway patrol, highway State Police (United States), patrol and is the primary law enforcement agency charged with in ...

have all adopted the Glock 37 and .45 GAP. As of 2025, the New York State Police, South Carolina Highway Patrol, and Florida Highway Patrol no longer issue firearms chambered in .45 GAP. The

Pennsylvania State Police The Pennsylvania State Police (PSP) is the state police, state police agency of the U.S. state of Pennsylvania, responsible for statewide law enforcement. The Pennsylvania State Police is a full service law enforcement agency which handles both ...

also carried the Glock 37 from 2007, but, due to ammunition supply problems, replaced them in 2013 with the fourth generation Glock 21 in .45 ACP. After recall issues with the new fourth generation Glocks, the Pennsylvania State Police switched to the SIG Sauer P227 in .45 ACP.

References

External links