.45 GAP

The .45 G.A.P. (often called the .45 GAP) pistol cartridge was 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 but was shorter to fit in a more compact handgun. G.A.P. is an acronym for "Glock Automatic Pistol", and the .45 G.A.P. is the first commercially-introduced cartridge identified with Glock.

Development
The concept of a shorter .45 ACP round is not new; previously there was the .45 H.P., no longer in production. But the .45 GAP had the backing of a major firearms manufacturer, which greatly increased its chances for success given Glock pistols' extraordinary popularity and market share, particularly among law enforcement personnel.

The .45 GAP is the same diameter as the .45 ACP pistol cartridge, but is shorter than the .45 ACP – and even slightly shorter than the overall length of the 9x19mm Parabellum and .40 S&W – and uses a small-pistol primer as found in smaller calibers such as the 9 mm Para, instead of the large-pistol primer as found in most commercial loadings of the .45 ACP (a few manufacturers occasionally use small-pistol primers on some of their .45 ACP offerings).

In order to provide terminal ballistics on par with the standard 230 grain .45 ACP "factory load" despite using a lighter (185 or 200 grains) bullet, the .45 GAP was designed to operate at a higher standard pressure, roughly equivalent to the higher pressure found in the .45 ACP "+P" rounds – although both the .45 GAP and the .45 ACP +P have considerably lower pressures than those found in both the 9mm and .40 S&W rounds. The designer was only able to achieve the desired pressure and resulting velocity through clever powder selection, since the .45 GAP has a much smaller cartridge volume than the .45 ACP.

Finally, the .45 GAP is offered in "flattened nose" (or "truncated") standard bullet configuration rather than the pure "round nose" bullet design found in the standard .45 ACP. The "flattened nose" bullet configuration, which resembles "SWC" or "semi-wadcutter" target bullet design, was first popularized for semi-automatic pistols in the .40 S&W design, which took advantage of modern semi-automatic pistol designs which can reliably feed flattened nose bullets. The flattened nose bullet is considered a more effective bullet design, short of expanding or hollow-point designs, than round nose bullets since it will "cut" through its target instead of deflecting around harder tissues and bones.

The full frame sized Glock 37 pistol (medium sized relative to other pistols) was introduced by Glock to use the .45 GAP and was followed by both medium (G38) and "baby" (G39) versions. Width of each of the GAP pistols is listed by the manufacturer as 1.18" compared with 1.27" for the "baby" G30.45 ACP, indicating Glock was not only able to shorter the front to back dimensions, but also the width of the grip. The GAP versions only hold 10, 8, and 6 rounds respectively, however, compared to 12 and 10 in the Glock 21 and 30, respectively. The introduction of "SF" .45 ACP versions of the full-sized Glock 21 and "baby" Glock 30 have lessened the need for the .45 GAP in terms of satisfying the requirements of law enforcement agencies which must offer sizes for smaller hands, but the GAP Glocks remain thinner (comparable to the "single stack" Glock 36 in .45 ACP) and hence more attractive for some shooters. The question remains, however, in light of the introduction of thinner gripped .45 ACP's, such as the Smith & Wesson M&P .45, and shorter (front to back) gripped .45 ACP's, such as the Springfield Armory XD .45, whether the market niche for the .45 GAP will remain large enough to support it.

Although .45 GAP remains difficult to find in mass-marketing outlets and at many gun stores, it is available on-line from many sources and, when discounted, is available for an approximately 10% premium over "factory loaded" .45 ACP. When compared to "self defense" .45 ACP rounds, the price difference virtually vanishes.

Perhaps the main advantage of the .45 GAP is the greater suitability of almost any factory .45 GAP loading for self-defense versus .45 ACP, which is often offered in "target" loads and is most commonly found in traditional "round nose" design. It is similar to .40 S&W in this regard - almost all available factory ammunition is loaded for law enforcement or self-defense usage, and not for target practice.

Other comparable rounds to consider are the .40 S&W and the 10mm. Although 9mm is available in high-performance rounds, the .40 S&W and the 10mm are almost always loaded "hot," while the .45 ACP has been considered effective even in "lighter" loads due to its larger (than 9mm or .38 special) diameter and heavier bullet weight.

Initial market response to the .45 G.A.P. cartridge
Gun Tests Magazine ran an article in the February 2005 issue comparing five commercial loadings of .45 G.A.P. ammunition when fired through the Glock 37 polymer-framed pistol. All of the brands failed to meet the desired 2-inch (51 mm) accuracy at 50 feet (15 m); the groups ranged from 2.5 to 3.5 inches (64 to 89 mm). 4 of the 5 loads generated velocities on par with the .45 ACP +P, and these loads were considered uncontrollable by the testers, as the recoil generated was extreme for the weight of the pistols chambering the round. The one remaining load, firing a 185-grain (12 g) bullet at an average velocity of about 950 FPS(290 m/s), was considered to be at the upper limit of controllability. The reviewer theorized that the potency of the .45 G.A.P. factory loads was an attempt to avoid derogatory comparisons between the .45 ACP and the .45 G.A.P., such as was experienced when the .40 S&W was introduced as a lower recoil substitute for the 10 mm Auto.

Current market response
After extensive testing four state law enforcement agencies have decided to adopt the .45 G.A.P. as a replacement to their current issue 9x19mm's (NY) or .40-caliber weapons (GA, PA, SC). The New York State Police, Georgia State Patrol, Pennsylvania State Police, and South Carolina Highway Patrol have all adopted the Glock Model 37 and .45 G.A.P.

Due to its acceptance by law enforcement and the popularity of subcompact handguns for concealed carry, more manufacturers have decided to produce pistols chambered in .45 G.A.P. As of 2007, Para-Ordnance and Springfield Armory are offering their micro-1911 series in .45 G.A.P. Springfield Armory is also offering its XD line in .45 G.A.P.