The .45 GAP Glock 37 Pistol
By Chuck Hawks
It seems that for some folks the .40 S&W cartridge, intended to fill the "gap" between the 9x19 and .45 ACP cartridges, and do it in a medium frame (9mm size) pistol, was not enough. Glock has responded to the perceived demand for a true .45 caliber cartridge in a medium frame pistol by introducing the first cartridge bearing the Glock name and a gun in which to shoot it. The cartridge is the .45 GAP (Glock Automatic Pistol), and the gun is the Model 37.
The new cartridge is necessary because the old .45 ACP simply will not fit in a 9mm size pistol. And people with small hands, particularly female police officers, sometimes have trouble handling pistols with .45 ACP size grips.
The .45 GAP was developed as a joint venture with Speer. It is a unique cartridge, based on no existing case. In form it is a typical rimless, straight wall, pistol case similar in length to the 9x19. It has a slightly rebated rim diameter of .465" and a cartridge overall length of 1.07". Bullet diameter is .452", the same as the .45 ACP.
Note that the .45 GAP is not interchangeable with the .45 ACP and its cases cannot be formed from .45 ACP brass. The two cases are dimensionally different, use different size primers, and the internal case profile of the .45 GAP is quite different from that of the .45 ACP.
The new case is unusual among big bore pistol cartridges in that it uses a small pistol primer. This is necessary to avoid over-igniting the powder in the small volume case. The maximum average pressure of the new cartridge has been set at 23,000 psi, which is the same as the MAP of .45 ACP +P ammunition.
This short .45 was designed to use bullets weighing 200 grains or less. With bullets weighing 185-200 grains it equals the performance of standard .45 ACP factory loads, although the old Colt cartridge is superior with heavier bullets. This minor ballistic miracle is achieved in a case of reduced capacity by using an advanced powder.
Speer .45 GAP factory loads include 185 and 200 grain bullets. The 185 grain bullets are loaded to a muzzle velocity (MV) of 1020 fps and muzzle energy (ME) of 427 ft. lbs. The 200 grain bullets are loaded to a MV of 950 fps and ME of 401 ft. lbs. A variety of bullet types are offered, suitable for practice and duty use. Federal and Winchester have introduced similar .45 GAP factory loads, and other ammunition manufacturers are expected to follow suit.
The new Glock pistol for the .45 GAP cartridge is the Glock 37. A simplified description of the new pistol for persons familiar with the Glock line is a Glock 17 (9x19) frame modified to accept a Glock 21 (.45 ACP) slide.
Of course, the development of the new pistol was not that simple, and the slide is actually not quite the same as a G21 slide, but that's the general idea. The .45 GAP cartridge generates more recoil momentum than the 9x19, so the new slide was necessary to retain the slide balance and reliability for which Glock pistols are justly famous.
Here are the specifications for the G37:
In appearance there is no mistaking that the G37 is a Glock. It has the typical boxy slide, ergonomic grip angle, double stack magazine, squared-off trigger guard, and controls as other Glocks. The front corners of the slide are beveled in a manner similar to the sub-compact Glocks. The finish is over-all matte black. The G37 accepts the usual Glock accessories.
In operation the G37 is identical to other Glocks, and so is the takedown procedure. It has the typical long trigger pull and similar inherent accuracy. The Glock family remains just about the simplest pistols to operate that I know of, and their reliability is legendary. Big bore fans with small hands should be pleased with both the .45 GAP cartridge and the Glock 37 pistol that shoots it.
Copyright 2004 by Chuck Hawks. All rights reserved.