.45 GAP expirement

I mentioned on my Facebook page yesterday that I had experimented with shooting .45 GAP cartridges out of my .45 ACP revolver, a Smith & Wesson 625.  The genesis of the idea is located in the preceding link; however a short summary is that the GAP round has a shorter OAL than the .45 ACP round, and also uses small pistol primers instead of large.  Taken together, that means that in theory the GAP rounds should be easier to reload quickly than the ACP and that you can detonate the primers with a lighter trigger pull.

Yesterday I headed out to Atlanta Conservation Clubwith my 625 and 59 moonclips.  I had 300 rounds of good old .45 ACP ammo, which I ran though the gun before I shot the 50 rounds of .45 GAP I had purchased.  I wish I had bought more GAP ammo, but the goal of the test was to see if there was an appreciable difference in reload time between the ACP rounds and the GAP rounds. To test reload times, I shot one of my favorite drills, the FAST Drill from Pistol Training.Com. My personal best on the FAST Drill using a semi-automatic pistol is 5.22 clean – meaning that I kept all the shots on the target where they’re supposed to go. Yesterday, I shot it several times using the 625. It’s a good drill for revolver shooters actually: start with 2 rounds loaded in the gun, at the buzzer fire those two into the index card/head box, reload with a full moonclip of six rounds and fire four more shots into the 8 inch body circle. At the end of each string you’ll have the two rounds in your gun that you’ll need to start the next string.

With .45 ACP cartridges, I was able to average about 7.5 seconds for the entire drill, with my FASTest (haha) time being a 6.81 run. After 10 runs, I switched to the GAP rounds, where my fastest time was 7.01 seconds, with an average run time of 9.2 seconds.

Why were the GAP runs slower? I think two factors contributed to this: 1) the moonclips are designed for .45 ACP brass, not .45 GAP brass. The GAP brass is slightly smaller in diameter in the area where it clips in to the moonclips, which means while it’s easier to enclip and declip the rounds, they GAP rounds have a bit more wobble than the ACP rounds when you’re trying to reload them. For casual plinking that’s not a problem, but when you’re almost throwing the moonclip at the gun because you’re in a hurry, it can be. The second issue was caused by the fact that the GAP rounds are loaded to a much higher pressure than the standard .45 ACP rounds. This is so that the shorter .45 GAP cartridge can achieve similar terminal ballistics to the larger .45 ACP. That lead to more felt recoil and muzzle blast, which caused me to slow down a little bit to make sure my hits were going in.

I could eliminate the wobble problem with the .45 GAP brass though. TK Custom makes a .45 GAP moonclip for the 625, but get this: it’s almost 70 bucks for a pack of 10 moonclips. That means each moonclip is 7 bucks! Compare that to Wilson Combat .45 ACP moonclips, which give you a pack of 5 for about 4 dollars from Brownells. It’s also worth noting that the Wilson Combat moonclips are the most expensive “non-match” moonclips you can buy, and they’re still significantly more cost effective than the GAP moonclips. Ultimately, using GAP ammo in my 625 doesn’t really seem to offer an advantage over .45 ACP ammo, which is what I had suspected to begin with. And besides, if it was such a hotrod idea, wouldn’t Jerry Miculek already be doing it?


  1. The .45 GAP has the rim and groove diameter of a .40 S&W , so maybe moon clips for a 10mm would work.

  2. Maybe, but for the most part this is trying to find a hardware solution to a problem with my mechancial skills. If I want to reload faster, I need to practice reloading, not search for exotic gear combos.

  3. Hmmm……I have a powered case trimmer for my Dillon, and while I’ve always used it on rifle brass, I don’t see any reason why it wouldn’t work on pistol brass as well. I’ll have to measure the cutter and see if it’s large enough to handle 45 ACP brass. Seems to me that one could tailor their ACP brass to whatever length works best and not have to put up with the length dictated by Glock. The 45 ACP case is .898″ long, and the 45 GAP is .775″, not quite 1/8 inch shorter. I wonder what he optimum 625-reloading case length is, and is there a bullet/powder combination that would allow making USPSSA major safely.

    Ever looked at 45 Auto Rim cases? Might auto rims in a speedloader offer a shorter reload time?

  4. There is a chance that you were not much slower with the GAP than with the ACP (if for example you did 1000 runs instead of just 10). Do you want to post the raw reload time and I can quickly run it through statistics software?

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