Let me say this. I worked in a gun shop part time. The shops in our area.... you might find a box of 45 GAP on a shelf, maybe not. The Distributors I talked to would yawn and quickly change the subject, when you mention the GAP cartridge or guns. Frankly, it was an idea that allowed you to put a 45 caliber cartridge in a 9mm or 40 cal frame gun, and have "close" to a 45 ACP performance. In other words you get the power of a Glock 21 in the frame size of a Glock 17 or 22. OK, I understand. But the problem I see is that it's a high pressure cartridge, just like the 40, and the recoil is snappy. More than the 40 or the 45 ACP. They dropped the bullet weight to make it faster, and have to cram fast burning powders into a small cartridge case to make it perform anywhere near the 45 Auto, that they were trying to match.
"My Opinion", is why waste your time and money. Buy a 45 or a 40. The ammo selection is much better and certainly more plentiful. The gun selection is also. I talked to a Glock rep about Glock comming out with a single column - full sized pistol, that was slimmer than the G21 and held say 9 or 10 rounds in the single column mag. It would be a slimmer, easier to handle version of the Glock in 45 ACP. He said they had discussed this, but Gaston Glock wanted a company proprietory cartridge with the name GLOCK, like for instance, the 357 Sig. And that is the ONLY reason they came out with it and marketed it as a new alternative to the 45 ACP with a slimmer, trimmer frame. Does it work, probably, but why go through the hassle of buying mags, ammo, etc, that are limited to only a few guns, and ammo that is as hard to locate as teeth on a chicken. The State Park Rangers here, carry them on duty, and constantly gripe about the lack of ammo, the high price of it when you find it, and lack of accesories for the Glock GAP pistols. Just my opinion.