Web Blast: The .45 Gap

| Uncategorized |

By John Taffin

From The September/October 2008 Taffin Tests Column

Taffin 1

American pistoleros are a tough crowd to please. Consider just some of the cartridges arriving in the last half of the 20th century. On the sixgun side of the ledger the .44 Magnum and .454 Casull are doing well; a dedicated group of cartridge connoisseurs espouse the .32 Magnum, .41 Magnum, .475 Linebaugh and .500 Linebaugh; the .445 SuperMag seems to be holding on by a thread. As of this writing the excellent .480, which was developed in the last year of the last century, is not cataloged by Ruger as a Super Redhawk, but many hold out hope for a five-shot Bisley Model. The .22 Jet, .401 PowerMag, .360 DW, .357, .375 and .414 SuperMags are basically dead.

Semiauto shooters are not any kinder to new cartridges. Try to find a 9×21, 9×23, 9mm Magnum, 10mm Magnum, .38 Casull, or .41AE chambered semiauto. Only Glock offers the once highly heralded 10mm, Wildey still offers the .44 AutoMag and .45 WinMag, while the .50AE is still found in the Desert Eagle. The one very bright spot seems to be the .40 S&W which has been adopted by many law enforcement agencies.
Reams of paper have been exhausted arguing the merits of various auto cartridges. When I was a kid it was always the 9mm and the .45 ACP. After 1990 it became the .40 S&W against the .45 ACP. The .45 held the edge in power, however the .40 was found in a smaller package allowing high capacity magazines in a reasonably sized grip frame.

Taffin 2

John filled in the gaps this past summer shooting (left) Glock 21SF .45 ACP and 38 .45 GAP,
and (right) Springfield Armory XD Tacticals in .45 ACP and .45 GAP.

Taffin 3

An excellent way to carry a .45 GAP Model 38 is in CrossBreed Holsters’ SuperTuck

Gap It

The next evolutionary step in semiautos seemed to be putting a new .45 cartridge with the power of the .45 ACP in a semiauto the size of .40 S&W. The result is the .45 GAP. GAP stands for Glock Automatic Pistol, however it can also be regarded as filling in a real gap.

Some shooters have a difficult time reaching the trigger on a 1911, while a double stack, high capacity, is either very bulky or impossible for the same shooters to reach the trigger. Would it be possible to come up with a new .45 with the same ballistics as the .45 ACP but in a shorter case, which would allow a smaller grip frame? Powder development is eons away from where it was in 1905/1911 so the prospect of actually shortening the .45 ACP looked to be within reach; that reach resulted in the .45 GAP.

The .45 GAP was suggested by Gaston Glock and developed by Speer. A look at other semiauto cartridges shows the .45 GAP with its case length of .755” is shorter than the .45 ACP by .143”, .095” shorter than the .40 S&W, and about the same length as the 9mm. The .45 GAP may appear to be simply a shortened .45 ACP, however it definitely is not and .45 ACP brass cannot be used to make .45 GAP cases. Not only is the .45 GAP shorter than the .45 ACP, it also has a slightly rebated rim, the extraction cannelure has a different angle, the internal wall profile differs quite markedly to allow the seating of bullets in the shorter case, and the .45 GAP uses small pistol primers, not the large primers found in the .45 ACP.

The .45 GAP was originally designed to fit the medium-sized Glock 37. It is now also offered by Springfield Armory in their XD, and both Springfield Armory and Para-Ordnance offer miniaturized 1911s chambered in the .45 GAP. My test guns are the Springfield XD and the Compact Glock 38. Glock also now offers the Sub-Compact Glock 39. As this is written at least two dozen law enforcement agencies have adopted the .45 GAP, including the New York State Police, the Pennsylvania State Police, the South Carolina Highway Patrol, and the latest, the Georgia State Police. During my lifetime I have seen the switch from the .38 Special to the .357 Magnum to the 9mm to the .40 S&W. In recent years more and more agencies have gone to the .45 ACP, so it will be interesting to see the future of the .45 GAP. It will be a tough, perhaps impossible, uphill battle to push the .45 ACP aside.

Taffin 4

A comparison of the .45 GAP and .45 ACP.

Taffin 5

A progression of .45s: .45 Colt, .45 S&W, .45 ACP, .45
Auto Rim,.45 WinMag, .454 Casull and .45 GAP.

The Load

SAAMI specs for the .45 GAP give a maximum of 23,000 psi, which is the level for +P .45 ACP. Factory loads for the .45 GAP are basically offered with the same weight bullets as the .45 ACP which means up to 230 grains in weight. I had three factory loads at my disposal, American Eagle 185 TMJs which clocked out at 1,028 fps from the Springfield Armory XD and 942 fps from the Glock; Winchester’s 185 Silver Tip HPs, 997 fps and 893 fps respectively; and Winchester’s 230 JHP, 885 fps and 862 fps, also respectively. The Winchester Silver Tip loading proved to be the most accurate in both autos, with five shot groups of 13⁄4” for five shots at 50 feet.

For reloading the .45 GAP I used Starline brass, Hornady’s 185 and 200 XTP-JHPs, and Sierra’s 185 JHC and 200 FMJ with all loads being ignited with CCI’s #500 small pistol primers. One load was assembled with Oregon Trail’s 200 SWC with 4.5 grains of Hodgdon’s TiteGroup resulting in an excellent practice load of over 900 fps. For powders in addition to TiteGroup, I also used Hodgdon’s Universal, and LongShot, as well as Alliant’s Power Pistol and Unique.

I filled in the gaps this past summer by shooting a pair of .45 GAPs and comparable versions chambered in .45 ACP. From Springfield Armory came a pair of XD Tacticals, one in .45 ACP and the other in .45 GAP; and from Glock, a Model 21SF .45 ACP and a Compact Model 38 chambered in .45 GAP. I have been a fan of the 1911 and the .45ACP for more than a half-century. There is such a traditional aura around John Browning’s original cartridge and 1911 platform that in some circles it is almost heretical to suggest any changes to either one. In the past two decades we’ve seen many non-1911 style .45 ACPs offered and well received by the shooting public as well as law-enforcement. Glock took it one step further by also changing the cartridge.

Taffin 5

Typical groups fired with the .45 GAP Glock Model 38.

Taffin 8


when the shooting starts I would feel most comfortable whether my hand is wrapped around a 1911, Glock or XD; and I also would not feel the least bit handicapped if the .45 happened to be a GAP instead of an ACP. I like the idea of the .45 GAP and I also like the very slightly smaller grip frame the shorter cartridge allows.

One of the great attributes of the 1911 is how easily it tucks into the waistband and stays in place; not so with either the Glock or XD. For concealment use with these we need an inside the pants holster. For the Glock Compact Model 38 that holster has turned out to be one of CrossBreed Holsters’ Super Tuck Deluxe. There are several things special about the design of this holster. The holster body itself is of Kydex which is molded to hold the gun securely, allow a smooth draw, and its rigidity also allows the gun to be easily re-holstered. The part of the holster that rides against the body is leather which makes it much more comfortable for extended periods of wear than would be afforded by a Kydex backplate. This is an excellent design which can also be adjusted to ride higher or lower on the belt. Good stuff!

For more info:

Complete Test Fire Loads Data

Test Fire
The .45 GAP Springfield
Armory XD
Armory XD
Glock Model
Glock Model
Load MV 5 Shots/50
Ft (XD)*
MV 5 Shots/50
Ft (Glock)*
Factory Loads:
American Eagle 185 TMJ 1,028 2-1/4 942 2 1/8
Winchester 185 SilverTip 997 1-3/4 893 1-3/4
Winchester 230 JHP 885 2 862 2-1/2
Handloads: Hornady 185 XTP-JHP:
4.5 gr. Hodgdon’s TiteGroup 888 2-1/2 855 1-1/2
6.0 gr. Hodgdon’s Universal 939 2-1/4 839 1-5/8
7.0 gr. Hodgdon’s LongShot 986 2-3/8 895 2-1/4
6.0 gr. Alliant Power Pistol 819 2 749 2-1/2
6.0 gr. Alliant Unique 918 1-7/8 834 2-1/2
Handloads Hornady 200XTP-JHP:
6.0 gr. Hodgdon’s Universal 967 1 953 2
6.5 gr. Hodgdon’s LongShot 921 1-1/2 883 2-1/2
6.0 gr. Alliant Power Pistol 840 1-3/8 787 1-1/4
6.0 gr. Alliant Unique 826 1-3/4 750 2
Handloads Sierra 185 JHC:
6.0 gr. Hodgdon’s Universal 966 1-3/8 902 2-3/8
7.0 gr. Hodgdon’s LongShot 986 2-7/8 895 2-1/4
6.0 gr. Alliant Power Pistol 814 1-5/8 798 1-1/2
6.0 gr. Alliant Unique 950 2-1/2 880 2
Handloads Sierra 200 FMJ:
6.0 gr. Hodgdon’s Universal 936 2-1/2 849 1-1/4
6.5 gr. Hodgdon’s LongShot 865 1-3/8 807 1-5/8
6.0 gr. Alliant Power Pistol 802 1-7/8 735 2-1/4
6.0 gr. Alliant Unique 804 2-1/4 727 2-1/2
Handloads Oregon Trail 200 SWC:
4.5 gr. Hodgdon’s TiteGroup 938 2-1/4 913 2-1/2
* Groups in inches.

We think you'd be interested in this, too

Sharp Dressers!

Havalon Knives are well known in the hunting and fishing segments of the outdoors market for pushing the envelope of replaceable scalpel-bladed knives...
Read Full Article
The Long, Short...

One of my colleagues in Florida who has been a semi-auto guy probably from day one admits he’s not that adept with a wheelgun, which is fine, because...
Read Full Article
Advantages Of...

It’s roughly two weeks to my yearly pilgrimage to the NRA’s Whittington Center and my ammo stash is running low. I need to manufacture some ammo … and...
Read Full Article