Has anyone tried chambering an AR for .45 Long Colt?

[Moleman-]

pistol caliber ars dont have gas ports. There blow back.

MOST pistol caliber uppers are blowback, but not all. Google 9mm, 40S&W, 10MM, 45acp, 357Mag, 357SIG, 44mag, 45WM, or 9x23 DI uppers and you should be able to find info on them. I have 3 blowback 9mm's and 3 DI 9mms. The 9mm DI barrels have a gas port about 1.25" in front of the casemouth step in the chamber and use a 5.45x39 BCG (or opened up 223 bolt) I mostly shoot the blowback guns as they're cleaner, and less picky about ammo.

[Baltimoreed]

I have several .45acp blowback pcc’s that are great. The CMMG system is a lot nicer than the old Olympic Arms blowback stuff but I don’t see why you couldn’t do a .45 Winchester magnum. Would take some r&d on your loads and buffer springs. Good luck.

[perotter]

pistol caliber ars dont have gas ports. There blow back.

Except the .45 LC can and is loaded fairly heavy. Think std 45/70 range. I'd think blow back for this round might not be the best idea.

Of course the great range of loads used in this round make less than ideal as a gas gun. Personally if trying to design for an action type in an AR with this round, I'd first look would making it an inertia system. And a second of choice of primer activated like the Clarke was.

With one or the other then any round that made 10,000 psi would work. Even blackpowder loads would work.

[Earlwb]

I don't find any AR cartridge with a rim diameter exceeding .473 inches. The .45 Colt uses a .512 inches dimension. The main reason for that is that the bolt face would not have any locking lugs left to safely keep the bolt locked when firing. The .512 inch rim diameter exceeds the bolt face size. There have been some rimless versions of the .45 Colt made though. Those use a rebated rim thus would fit the bolt face Ok. The rebated rims tend to be around .443 inches thus giving the bolts more locking lug area. .473 inch tends to leave just enough sized locking lugs to work.

[country gent]

With an AR15 platform and the pressures the colt can be loaded to ( black hawk levels) I would be concerned with the barrels shank tenon wall thickness. The body of the 45 co;t is around .480 the body of the 223 is around .380. Going to a AR10 would negate this issue but in a AR 10 I can think of better rounds.

The other I see is the difference in cartridge lengths effect on feeding.

I have bored ar bolts for 762 x 39 or ppc ( .441) and the supporting ring gets very thin with the .520 face it would be non existant. Another would be "adjusting" the new extractor for the larger rim

[Moleman-]

Still think it's "do"able if you're motivated enough. There's always one of the WSSM bolts/extensions/uppers which would be more than large enough for the rim dia or going with an ar10/LR308 platform as already suggested. With Olympic being closed again, the WSSM bolt/extension/upper or 22-250 bolts/extensions are going to be much harder to source though as the other players generally don't sell just parts. They may be willing to make one for you is you throw enough money at it. FWIW the 22-250 bolts/extensions use the same 13/16"x16tpi .620" ish barrel tenon of the 5.56 barrels and have a .570" wide bolt head face v/s the 5.56 .530"ish. The bolt pocket would still be very thin, but not much different than a standard 450BM bolt. There are quite a few 45 raptor uppers out there floating around using the 22-250 bolts/extensions and the 13/16"-16tpi tenon doesn't seem to be an issue. All that said, something like a 45wm would be a much easier option and could use 450BM bolt/extensions and 450BM magazines with the feed lips bent in slightly and possibly a spacer depending on COL. I have a 44x1.6" off of 30-06 brass (like a rimless 445SM with a larger base dia) that runs off of 450BM parts, and a 44x1.8" and 40x1.8" (400FUW) again both off of 30-06 brass that use the 22-250 bolts/extensions and 450BM mags.

[VariableRecall]

Still think it's "do"able if you're motivated enough. There's always one of the WSSM bolts/extensions/uppers which would be more than large enough for the rim dia or going with an ar10/LR308 platform as already suggested. With Olympic being closed again, the WSSM bolt/extension/upper or 22-250 bolts/extensions are going to be much harder to source though as the other players generally don't sell just parts. They may be willing to make one for you is you throw enough money at it. FWIW the 22-250 bolts/extensions use the same 13/16"x16tpi .620" ish barrel tenon of the 5.56 barrels and have a .570" wide bolt head face v/s the 5.56 .530"ish. The bolt pocket would still be very thin, but not much different than a standard 450BM bolt. There are quite a few 45 raptor uppers out there floating around using the 22-250 bolts/extensions and the 13/16"-16tpi tenon doesn't seem to be an issue. All that said, something like a 45wm would be a much easier option and could use 450BM bolt/extensions and 450BM magazines with the feed lips bent in slightly and possibly a spacer depending on COL. I have a 44x1.6" off of 30-06 brass (like a rimless 445SM with a larger base dia) that runs off of 450BM parts, and a 44x1.8" and 40x1.8" (400FUW) again both off of 30-06 brass that use the 22-250 bolts/extensions and 450BM mags.

I think I can save the experimentation for a lot braver people. Now, adopting a loading gate and tube magazine adapter would be another thing, that's for certain.

[bigwagon]

Sounds like it would be quite a project making a rimmed cartridge work. But for a lot less effort I think a similar goal could be realized with an upper in 458 Socom.