Crazy ideas

While at the Tri-State, I managed to keep my ears open enough to hear some interesting things, one of which I’m probably going to try to see how it works out. One of the few wheelgun shooters at the match (a master class ESR shooter) was running a weird load in his 625: .45 GAP loads set to make the power factor required.

For those not familiar, .45 GAP was introduced as a “solution” for shooters looking for .45 ACP ballistics in a cartridge the same OAL as a .40 S&W. It has enjoyed moderate popularity, as at least one or two large PDs carry Glocks chambered in the gun, and there are also a couple micro defensive pistols chambered for it.

There are some benefits to running .45 GAP in a 625, or so I was told. The first benefit is that the Glock Automatic Pistol (GAP) round has a shorter overal length than the ACP round. Generally speaking, when loading from moonclips, shorter=better. The second benefit I had explained to me was the most interesting; .45 GAP uses small pistol primers instead of the large pistol primers employed by the ACP round. This has two positives: 1) you can actually find small pistol primers, 2) small pistol primers don’t require as forceful a hammer strike for reliable igniton, which means you can get an even lower trigger pull set up on the gun.

The real question though is whether the gain is really worth it. I’m skeptical of trying to create equipment solutions to questions of skill, especially when the ACP seems to work for pretty well for that Miculek guy.

That being said, I am going to pick up a box of 185 grain (my favorite bullet weight for ACP rounds) .45 GAP just to see what happens. That is of course barring someone saying in comments that it’ll vaporize my gun or something.


  1. This master class shooters scores speak for themselves. IMO There is nothing wrong with experimentation. But for a guy like me (a Marksman ESR shooter) making the above mentioned changes to my load and setup would be academic in regards to score. I expect that the average shooters ability to exploit a trigger pull that was to light to ignite large primers would not even be measureable. The last match I shot made me realize that I need to learn a few things about managing my trigger. That being I don’t effectively engage moving targets without staging my trigger for the shot, and, although I can do this pretty well in my living room, at the range under stress, I fail miserably. This will probably improve with experience, But I wonder if constatly fiddling around with my trigger pull weight wouldn’t impede my progress. Anybody got any EXPERIENCE here?

  2. Constantly fiddling with your trigger is a bad idea. Shooting fundamentals first, gear second.

    Plus, Jerry Miculek actually said that the best trigger job for a revolver was to shoot 3000 or so rounds through it.

  3. Crazy idea indeed! To put an Austrian designed round through a .45acp requires penance.
    You are to face Ogden, UT while transcribing by hand the Holy Writ of:


    Only then will you be in the grace of John Moses Browning (PBUH).

    *pours self another port and sniffs “Whiggery!”*

  4. In his revolver trigger job video, Jerry says that his competition gun runs with a lighter mainspring and trigger return spring (available from Clark custom, naturally) and recommends a certain brand of primer (don’t recall offhand which) to ensure reliable ignition with the lighter strike.

  5. Every time I think you can’t come up with any more ridiculous gamer gun ideas, you have to go and start thinking again.

  6. I am having trouble seeing the “small pistol primers are easier to ignite” bit.

    All things being equal (to which I cannot say that I KNOW that the primer cups of large and small primers are made of the same material in the same thickness), it would require MORE energy to deform the smaller primer cup due to the resulting deformation angles being greater.

    If both require similar depth of firing pin penetration to ignite (seems logical), then large pistol primers will actually ignite from a lighter strike.

    If the small primer cups are THINNER, then all bets are off.

    Having said that, I use small RIFLE primers in my .38 Super Comp rounds as they clearly resist the high pressure better – without the primer flow that I sometimes see with small pistol primers.

  7. Long story short:

    Madman with gun shoots people.
    Madman with power (prime minister) wets pants, forces states to impose tough new restrictions on guns by threatening to remove federal road funding unless they comply.
    Madmen in gun lobby sell us down the river by agreeing that >10 rounds & >.38″ diameter projectiles “not necessary for competition in IPSC/IPDA”
    Other men in gun lobby stand up and shout – .45 allowed in Cowboy Action and IHMSA

    “just because” and “self-defence” have not been “sufficient reason” for handgun possession in Oz for a LONG time – membership of a recognised shooting club and competing in a recognised discipline are pretty much the only way to get to own a handgun.

    The ban on .45 is not tied to military calibre – it is a simple blanket ban on anything greater than .38″ unless you COMPETE in Cowboy Action or IHMSA.

  8. So you’re saying you’re going to fire .45 GAP out of a .45 ACP chamber? I don’t know if it will vaporize your gun, but I don’t think it will work. ACP chambers headspace on the case mouth, and so do GAP I’m pretty sure…and since GAP OAL is less, that’s gonna be weird. Not sure if you’re trying this in semi-auto or not, but I would think best-case is the cartridge slides forward to the chamber edge, your firing pin can’t reach it and you have to extract it with a cleaning rod. Worst case is the round is held in place by your extractor, actually does fire, causing an ill-fitting brass to pretty much rattle around, possibly rupture, and possibly breaking your extractor from all the extra load.

    I mean, I’ve heard of guys doing it by accident and not suffering for it…but I wouldn’t try it in any gun you particularly like.

  9. Ah, but DOM, he’s going to fire it out of a 625 – a revolver.
    I assume that means moon clips, so the round headspaces on the RIM.

    i don’t think you want to headspace on the case mouth in a revolver.

    I have seen a number of the locals use cut down cases in revolvers using moon clips. In their application they want short cases to make reloads faster and it DOES make a significant difference. I have never heard them mention using small pistol primers to allow a lighter trigger – they simply use the softest primers they can find. Typically that is Federal 100s.

  10. From what I gather the 625 did originally headspace off the case mouth, but S&W changed it to the rim some time later. I’m no revolver expert though.

  11. The 625 does headspace off the front of the round, so that if you wanted to you could fire the .45 ACP rounds without the moonclips, although extraction would suck. The GAP rounds should be okay to fire, as they will space off the rims using the moonclips.

  12. When firing the 625 without moon clips, it is best to shoot a few clips first, so the carbon build up in the cylinder helps get the headspace off the front of the cartridge case exactly right. If you don’t do that, you may find that your ignition is spotty. The really bad part of that is if you were to get a “hangfire”. That is a delayed ignition that may go off when the cylinder is not aligned correctly with the barrel. Depending on where it is, you may get lead spray or worse.

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