.45GAP in a .45ACP Pistol?

Tully Mars · Sep 8, 2017

Recently bought up an estate sale that was firearm/reloading equipment heavy. In it I now have about 500-800 rounds of virgin .45GAP brass. I know next to nothing about the GAP not being a Glock fan, other than it's designed to run at a higher pressure.
My question is can the GAP brass be used in a .45ACP, specifically in a 1911 and/or Ruger P89 if loaded to ACP load data?

If not, I guess I need to find out what it's worth and a buyer

kilibreaux · Sep 18, 2017

Well, the cartridge is obviously shorter by 0.138" (3.5mm) and the rim is smaller by 0.01" (1/4 mm) which means it will fit inside an ACP chamber. Even with the smaller rim the dimensional difference is so small as to be inconsequential...just 1/8th of 1mm in radius. The shorter case will also work for the same reason the .460 Rowland can also shoot the shorter .45 ACP round, in the 1911 and Glock, the rounds are "controlled feed" in that the rim is captured under the extractor during feeding. One can just as easily fire .40 S&W in a 10mm chamber, or 9mm in a .38 Super chamber with no problem at all.

Some will say it's hard on the extractor, or will have excessive headspace....we yes and no. It's not really hard on the extractor at all since the mass of a single cartridge is quite tiny, and with the cartridge inside the chamber and chamber walls holding it aligned, there is little strain on the extractor. As for excessive head space, that condition is completely misunderstood when discussing this situation. Because the cartridge is held against the breech face during chambering and beyond, "headspace" is perfectly preserved.

As for pressure, the GAP round is loaded around 2K psi higher than ACP to precisely duplicate ACP ballistics and thus give the person who wants to shoot ".45" from a 9mm size gun exactly that...the full power of a .45 ACP from a 9mm size pistol. The pressure difference is immaterial considering how low .45 ACP pressures are in the first place. One approach would be to load to .45 ACP O.A.L. and .45 ACP data, another would be to load "GAP" ammo and fire away. As for pressure, .45 ACP+P is also around 2K psi "hotter" than standard ACP, and .45 Super is up around 25-28K psi without any negative effects to any modern 1911 barrel.

taroman · Sep 19, 2017

Great write-up.
I, too, lucked into a bunch of GAP.
Been shooting it in my S&W 625 revolver.
Fits ACP moons, but a bit jiggly.
GAP moons are $$$, so won't be going there anytime soon.

titsonritz · Sep 19, 2017

taroman said:
Great write-up.
I, too, lucked into a bunch of GAP.
Been shooting it in my S&W 625 revolver.
Fits ACP moons, but a bit jiggly.
GAP moons are $$$, so won't be going there anytime soon.

This

FullMetalJerk · Sep 19, 2017

Tully Mars said:
Ruger P89

.45GAP in a P89?!? No! lol

Tully Mars · Sep 19, 2017

FullMetalJerk said:
.45GAP in a P89?!? No! lol

Like my OP said, GAP brass loaded to .45ACP specs.

FullMetalJerk · Sep 19, 2017

P89 = 9mm. You must be thinking of the P90.

BillM · Sep 19, 2017

45 ACP head spaces on the case mouth. If the extractor holds the GAP case against the breechface well
enough to fire, it will work. Would be like firing 380 in a 9mm--might work but not the way things were
designed. As someone mentioned, it would work fine in a moon-clipped revolver.

JeremyK · Sep 19, 2017

The .45 what?

2Wheels4Ever · Sep 26, 2017

My father, bless his heart, bought a high point 45, then proceeded to buy 45gap ammo. After asking me why his brand new gun was jamming, I proceeded to tell him that you get what you pay for.

He asked me to shoot it and gave me some ammo. He had no idea what 45gap was...thought 45 was 45.

I bought him a 1911 and told him to throw away the up.

Anyways, if 45gap won't blow up a highpoint, any other gun will handle it fine, just might hang up on you.