The .45 GAP

The idea is so deceptively simple that I’m surprised someone had not tried it before 2003, which is the year that Gaston Glock did try and success. In a world gone mad over high-capacity magazines on the one hand and big bore pistols on the other, Glock made a monumental effort to give shooters both. Most shooters are uncomfortable with a high-capacity, big-bore pistol and the double-wide magazine that is required. They are much happier with two columns of the shorter 9 mm or 40 S&W rounds. These are the people that I call Capacitonians, those who fill the air with metal and hope for the best. Their opposite number is the Caliberite, the worshiper of cavernous barrels and the massive projectiles that issue forth therefrom. Both would profit mightily from the application of the principles of marksmanship, but that’s another story. 

Glock and his designers simply shortened the .45 ACP case to 9 mm/.40 S&W length and inserted a typical .45 ACP bullet over a charge of powder. It used the same type of 9 mm magazine as typical guns of that caliber, of course it held a few less cartridges. Mechanically, the new pistol had to have a stronger, heavier slide and other mechanical modifications. But these were possible and Glock got them done. They offered small, medium and large versions of what was essentially the world’s first 9 mm-sized .45. The new cartridge was called the .45 GAP (Glock Auto Pistol) and ammunition makers started loading it quickly.

They say the measure of a cartridge is how many ammo makers produce the ammo and how many gunmakers build a gun for the caliber. Most ammo makers offer a .45 GAP round, but no other gunmakers currently offer a pistol in that caliber. There were a few XDs from Springfield and some really neat experimentals from Para, but if you want a pistol for your .45 GAP ammo, you have go to the source—Glock.

In short, the idea has not caught on particularly well. I believe Glock still sells respectable quantities of the guns, but there is no other option for the caliber. Most of that seems to be because “simply shortened the .45 ACP case” does not completely describe what happened. The designers had to fiddle with nearly every dimension of that case to make it work right and they obviously reduced case capacity. That simply means that a .45 GAP pistol will essentially reproduce .45 ACP ballistics—a 230-grain slug at 850 fps—but it does so at a sharply increased pressure level. And too much pressure is very hard on pistols—very hard.

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10 Responses to The .45 GAP

Lane wrote:
May 19, 2014

Gun and ammo makers periodically attempt to reinvent the wheel and the .45 Gap is a great example. Each new offering claims to do something no other previous chambering could, but in truth, shooters discover there is no benefit, either ballistically, tactically or economically, from their existing numbers. In the latter half of the 19th century through the first half of the 20th, we were gifted with chamberings which could fulfill every conceivable role a handgun could be called upon to perform.

Harry P. wrote:
January 01, 2013

2 of 2/Mr. Clapp: Furthering my comments in Pt 1 of 2, I do think there is a “reason for a modern bottleneck defensive pistol cartridge” along the lines of the somewhat mismanaged .357SIG. For not only might there be reasons to seek out a better performing cartridge of any type over the aforementioned .38 Super, 9mm and .40S&W, but a bottleneck, especially one of .357 or .355 caliber, could offer a number of specific advantages lacking in straight wall or slightly-tapered-case rounds. Decades ago, when reloading was nowhere as popular as it is now (and often looked upon only as the activity of a true hobbyist/enthusiast) and non-ammo-manufacturer-initiated “wildcat” cartridges were thought to be the provenance of only a small subset of that group, promising experimental concepts like the .38/.45 Clerke (a .45ACP case necked down to .357) were never really investigated to the degree that they might have been today. And even today, when advancements in both bullet and ammunition performance take place on an almost daily basis, things seen in the .38/.45 and now taken to a new level with the .357SIG (a .40S&W case necked down to .355), still require a great deal of explanation and support to demonstrate and convince people of their true benefits. The .357SIG is amazingly accurate and its fat-bodied/short-bodied configuration allows for very efficient burning of the powder charge it contains. As a result, it offers performance similar to (its design goal of) the vaunted 125gr .357magnum revolver cartridge. Its bottleneck configuration also allows for feeding with bullets of all types including those with almost flat and open-mouthed profiles. And its overall reliability is so good that this isn’t even a case of a round-peg-in-a-round-hole but of a pointed-peg-in-a-funnel. All of which makes for tremendous dependability and ballistic performance that puts this “modern bottleneck” cartridge in a range that few conventionally-shaped “defensive pistol cartridge”s can match.

Harry P. wrote:
January 01, 2013

1 of 2/Mr. Clapp: Maybe you should address the subject yourself but since posting my original comments in regard to Mr. “Missiletoe’s” implication that “the .45 GAP” was a “modern bottleneck defensive pistol cartridge” (which was wrong factually), I have been thinking over his belief that there is “no reason for a modern bottleneck defensive pistol cartridge” (a personal opinion that he is certainly entitled to) for while I respect him and whatever experiences have led him to think this, I am of the mind to think otherwise. First, I should make it clear (and I alluded to this in my first post here) that I am a big bore fan and believe strongly in the use of .45, .44 and even 10mm bullets for defensive purposes. That said, one needs to look at both the platforms in which these projectiles are launched and the recoil some of them generate, when looking at offering them as defensive weapons to the average person (even the average police person). As such, cartridges like the .38Super in earlier times, the 9mm in more recent ones, and the .40cal in today’s world come into play. While I am a huge fan of the Super, it has a checkered past in terms of recoil and accuracy. People (not always me) have questioned the 9mm for as far back as it has been entertained for such purposes. And (wrongly, I think) the .40S&W has been attacked for recoil and a lack of performance. However, I do find myself of the belief that at times, its accuracy potential has been only adequate when compared to either the .38Spl on one side or the .45ACP on the other. Therefore, a true “modern bottleneck defensive pistol cartridge” like the sadly unheralded and now almost unsupported .357SIG might actually be a good idea. But much like the non-bottleneck .45 G.A.P., it seems to have fallen into a mismanaged limbo along with other cartridges that were either misunderstood or misrepresented from the start and now only exist in a fading grey netherworld from which they will gradually disappear altogether.

Pete wrote:
December 31, 2012

I think the reason this has not caught on is because of peopole like me. I would love a mid-sized Glock in 45, but I am one of those who will only buy a firearm in a "common" caliber so I won't invest in the 45 GAP. Of course, I knew the .40 S&W would flop and the 10mm would be a huge hit, so maybe I am wrong about the 45 GAP also.

Harry P. wrote:
December 24, 2012

“Mack Missiletoe”: Obviously, and not intending to speak for Mr. Clapp, I would assume from the opinionated statement you have made here, that there would be no convincing you of anything about this cartridge and any attempt to do so would only result in pointless quarrelling. However, one point I would like to make is not theoretical or emotional but based on fact and therefore not subject to the kind of argument you appear to be looking for. The .45 G.A.P. is not a “modern bottleneck defensive pistol cartridge”. In fact, it is not a bottleneck cartridge of any sort. And I mention this only so that others who might read your comments are not mislead by your implication that it is. The .45 G.A.P. cartridge is actually based on a proprietary, non-bottleneck case that is of a size and a crossection at the mouth that is capable of accepting typical diameter .45 Auto bullets without bulging and is roughly the same length (not diameter) of the 9mm Luger (9x19mm); although it should be noted that the length of the loaded cartridge as originally conceived is somewhat shorter than that of the 9x19. The case has a much different cross section than would a conventional .45ACP case were it merely cutoff to this length (in fact, in its early literature, Speer, who developed the cartridge with Glock, warned against merely cutting down .45 Auto brass for a number of reasons) but none of these differences (or any of the others involving a reinforced base, a slightly rebated rim, a different extractor groove, and the use of a small pistol primer) make the .45 G.A.P. a bottleneck design. The whole idea behind the concept was to offer .45ACP-like performance in grip frames of the type associated with the 9mm, which generally offered increased-over-standard capacities yet still fit a wider range of hand sizes than would similarly higher-cap .45auto receivers. Perhaps not as historical as some things and certainly not a revolver but still of potential value to many people, nonetheless.

Mack Missiletoe wrote:
December 21, 2012

I hate this cartridge. No offense if you like it, but I see no reason for a modern bottleneck defensive pistol cartridge--especially when reloading. I'd rather enjoy reloading old revolver cartridges more than this--they at least have history; the .45 GAP has no use in my opinion. Feel free to convince me otherwise.

Harry P wrote:
December 17, 2012

Mr. Clapp: To me, the saddest thing about the .45 G.A.P. is how it was handled or should I say mishandled. Originally, the early prototypes shown to Law Enforcement were heralded as pretty much a Glock 17 size gun with a .45 caliber bore. I believe that by the time it was released, its top end dimensions would no longer fit into a typical, tightly molded holster for the 17. I will never blame them if this was necessary mechanically & it’s certainly not the end of the world for an individual buyer but for an agency that might have to buy 50, 100, 1000 or more new holsters along with the new guns (and fund an ammo switchout), it could be a budgetary deal killer. But the real problem, however, was with the ammo. I & others were told at the start that while it offered a bigger diameter, the G.A.P. would never achieve the true performance of the .45ACP. I heard this caveat from Glock factory people and one of the cartridge's original makers. He said that it could not be done. Other people heard this or read about it too. I could live with it because I still liked the bigger bullet concept & now you could put it in smaller hands without what some saw as a lessened capacity. But many officers figured if this was the case (something less the .45ACP effectiveness), then why bother. The public (who could buy the gun in bigger numbers than LE) was also less than thrilled. Then other ammo makers began offering loads that did approach the .45ACP and utilized really good bullet designs. But by then it was too late. People were confused. People didn’t care & people didn’t view the relationship of gun size (especially gun girth) to performance the way they had the 9mm/40cal/.45acp matter or even the 9mm/40cal/.357SIG. They either saw it as a gimmick or a failed experiment for by the time the “better” ammo came about, they were convinced that while the guns were scaled down, their effectiveness was scaled back & they wanted none of it. Too bad, for that is obviously not the case.

Dale wrote:
December 14, 2012

Since the New York State Police have adopted the .45Gap as their Duty Weapon and they are happy with its performance, it will probably be around for awhile.

Lawman wrote:
December 13, 2012

There is also a third type of person - a mix of the two called a "Capacicaliberite" someone who wants a large number of 45 rounds. Thank goodness there is the Glock 21 which gives both (14 rounds of .45)

rink237 wrote:
December 12, 2012

Although an innovative concept the .45GAP might become another obsolete cartridge simply due to the love affair with the .45ACP and why change pistols for a different cartridge that accomplishes the same thing as the .45ACP. I know one of the disadvantages of pistols chambered for the .45ACP was that the grip tended to be too large for shooters with small hands, the other being recoil. Where the GAP cartridge solves the problem for smaller handed shooters the recoil remains. I imagine the .45GAP will hang on to its niche much like the .357SIG has but I think Glock also hindered themselves in its acceptance by introducing the SF series for .45ACP and 10mm making those pistols more accommodating to shooters with smaller hands.