Up front, this is really going to sound like a dumb question! I picked up a Glock 38 a few weeks ago along with 500+ rounds of factory ammo (at a near give-away price). I like it and have been impressed by the mild recoil – although the slide on the G38 weighs about as much as a brick. I also have my eye on a pretty nice P245 locally at a decent price. Could GAP rounds be fired thru it on an occasional basis? Please be gentle if this turns out to be a really dumb idea!! I plan on getting the P245 anyway ...

No

Sounds like fun!

Your best bet would be ordering a custom barrel and finding the best recoil spring weight by trial and error.

It is not as hard as it sounds. I did this when converting a Glock 21 to .38 Super.

If you decide to go this route, let us know how it turns out.

quote:

Originally posted by GeoJelly:
I also have my eye on a pretty nice P245 locally at a decent price. Could GAP rounds be fired thru it on an occasional basis? Please be gentle if this turns out to be a really dumb idea!!

Nope. You cannot safely shoot .45 GAP in your .45 ACP handgun.

Other than the bullet diameter (.451"), .45 GAP and .45 ACP are not the same thing, and are not interchangeable.

It's not a .357 Magnum/.38 Special either/or type of situation.


Now, you could potentially have a gunsmith produce a custom .45 GAP barrel assembly to convert your .45 ACP P245 into a .45 GAP, like .38supersig is talking about. But that's a custom job, and you'll be paying a pretty penny for it.

This message has been edited. Last edited by: RogueJSK,

According to the information I have available, the various dimensions of the 45 GAP and 45 ACP cartridges are virtually identical except for the case length. If so, firing the GAP in a gun chambered for the ACP should be possible for the same reason that it is often possible to fire a 9mm Luger round in a gun chambered for 40 S&W or a 40 S&W cartridge in a 45 ACP gun.

The reason why it’s possible to fire those cartridges from larger chambers is that as the slide moves forward and picks up the round from the magazine, the rim of the case slips behind the extractor and the extractor holds the cartridge against the breechface. When the hammer is dropped or the striker is released, the firing pin hits the primer of the cartridge and fires it in the normal manner. Many shooters have reported having the experience of firing the wrong round in that manner, and it’s easy to demonstrate.

Assuming that the rim of the 45 GAP cartridge also slips behind the extractor of a gun chambered for 45 ACP, the conditions for firing the round would be even better because there would be no chance that the cartridge would move to one side far enough that the firing pin would not strike the primer in the proper place. The only thing that would prevent firing the GAP round in an ACP chamber would be if the cartridge rim wasn’t engaged by the extractor and it moved forward into the chamber too far for the firing pin to ignite the primer.

BUT NOTE: Despite all that, a cartridge should never be fired in a firearm for which it’s not chambered. That is one of the many fundamental firearms safety rules beyond “the four” that all shooters should know and follow. The practice may be unsafe for unknown reasons, including different pressure curves and how the gun is proofed.

Another solution if you want to shoot 45 GAP is to get your chamber sleeved to shorten the chamber by .128". Our military did this at one point to convert M1 Garands to.308. Swedish 1903 Browning pistols were sleeved from 9MM Browning Long to 9MM Browning short (380) for sale here. Properly done a broken case extractor can be used to pull the sleeve to go back to 45 ACP

Agree with Sigfreund's note. Issue isn't whether the inappropriare cartridge will go bang. It's the potential safety issues. Note I said potential. IMO, it's not worth the potential risk to the pistol and the shooter.

I inadvertently fired a .40 S&W in my .45 ACP 1911. It went bang. That was an accident though.

inadvertently fired a .357 sig round through a .40 226. Nothing bad happened, but no one had a clue where the bullet went.

quote:

Originally posted by GeoJelly:
Could GAP rounds be fired thru it on an occasional basis? Please be gentle if this turns out to be a really dumb idea!! I plan on getting the P245 anyway ...

Of course you can

Scenario 1) You have purchased a aftermarket barrel for you P245 that is chambered for 45GAP. There are no potential problems with this

Scenario 2} You want to load and shoot 45GAP in your existing P245 setup. This will probably work. As described above the case head slips behind the extractor as the cartridge is chambered. This is referred to as head-spacing on the extractor. While your firearm most likely will function this way, it is not the recommended way to fire a cartridge that is from a similar case family.

As a last ditch effort, with your life on the line, with nothing but your P245 and some GAP ammunition remaining, I wold have no problem doing it this way

All that said, if you plan on shooting 45GAP in an 45ACP designed firearm, I would purchase a second barrel.

Remember....Just because you CAN do something does not always mean that you SHOULD do it

You can fire the 45 GAP in the P245. I have done it on several occasions, and can not tell any difference between the GAP and ACP rounds from the same gun.I realize it is not recommended, as the P245 is not chambered for GAP, but it does work. Unless I find a good deal on a G-37/38/39, I have about 500 rds of mostly Federal HP loads to shoot up. Will probably split it between the 245 and several 220s.

Thanks, Gents, for the info and your wisdom. I would have posted a photo but the pix in the posting are too low quality. It looks like new except for some wear on the barrel hood. I think the 245's have/had a folded slide? It comes in the case with three mags - the guy started it at $650. It's down to 550 as (IMHO) nothing .45 sells well around here. It would fill a big empty spot in my smallish SIG collection - I had to sell my first P220 over 20 years ago ... It would also be a prime candidate, later this year, to have SIG blast the slide (if it's stainless?) and install night sites. I was impressed with the work they did on my most recent P230SL.

Re the Sig slide bead blasting. Yes, they do a great job. I have had five Sigs sent to them for this and they were all very well done.

A lot of shooters don't like the aesthetics of the two-tone effect. Originally, I didn't either. The bead blast doesn't photograph well. After I sent my first slide out, I changed my mind.

One benefit you don't see discussed is the effect on sighting. I use blackl/black sights and the blasted slide provides a beneficial contrast that aids in fast sight acquisition. At least with my eyes.

Even if the shorter and rebated-rim GAP fed from the magazine and is held firmly enough by the extractor to fire, it still isn't safe to fire the wrong ammunition in any firearm. The one exception is a highly improbable survival situation. If the zombie horde has breached the wired fence, you've expended all your other ammo and all you have left is your P245 and .45 GAP, then you've got nothing to lose by trying it.

Sorry for the thread drift, but whenever I see .45 GAP mentioned, all I can think about is Sgt. Jay Cook dropping a running man from a reported 70+ yards with his Glock 37.