The Glock 37 is a .45-caliber pistol the size of a 9 mm. Glock 17 and .40-caliber Glock 22. The Glock 37 fires a brand-new pistol caliber, the .45 Glock Automatic Pistol, known as the .45 Glock, or the .45 GAP. This caliber is very similar to the .45 Automatic Colt Pistol, known as the .45 ACP or .45 Auto. The .45 GAP uses a shorter, stronger cartridge case but fires exactly the same .451-inch diameter bullets to the same velocities as the .45 Auto. The big deal with the .45 GAP is getting .45-caliber performance and higher ammo capacity in a standard frame pistol. The .45 GAP is a brand new caliber, jointly developed by CCI-Speer and Glock. The .45 GAP and the .45 Auto +P both have maximum pressures of 23,000 psi. The higher chamber pressure of the .45 GAP allows the 4.5-inch Glock 37 to equal the velocity, energy, and momentum of a .45 Auto fired from a 5-inch barrel. The .45 GAP case is special and unique. The .45 GAP uses a small pistol primer, while the .45 Auto uses a large pistol primer. The Glock 37 has three safeties: trigger safety, firing pin safety, and drop safety. For the record, .45 Auto ammo cannot be used in the .45 GAP-caliber pistol. It is predicted that the Glock 37 will seriously challenge all of the large frame, .45-caliber autos, both polymer and steel frame. The Glock 37 will also join the wide array of .40 S&W and .357 SIG pistols for police departments wanting to improve on the marginal 9mm caliber. The .45 GAP will probably not replace the .40 S&W as American’s Police Caliber, but it will push the .45 Auto into further oblivion. The .45 GAP will give a third choice for those undecided between the .40 S&W and .357 SIG.