45 ACP Magazines in 10mm 1911?

[Rmiked]

I’m not going to do this but am curious how and why it works. I have seen numerous reviews and demonstrations of guys successfully using 45 ACP mags in 10mm 1911s. I’m assuming the interior frame-mag dimensions are the same for both calibers but not sure about that. But I would think the follower and feed lips would be caliber specific. In addition to this curiosity (putting 10mm cartridges into 45 mags) I would wonder about 9mm and 38 super? Could someone explain the difference in the 1911 magazine dimensions for different calibers? Do manufacturers machine the frame differently to accommodate the different width cartridges? Is the space (to accept the magazine) in the grip of a 9mm 1911 smaller than that same space in. 45 ACP 1911? There is such a big difference in the size of 9mm vs 45 that the frames must be machined with matching rectangular holes. But 10mm and 45 seem close enough to work? My question is basically the larger question of: Once 1911 was expanded to other calibers, what dimensional changes were made deviating from the original drawings for the 1911 in 45ACP?

[Dave Williams]

Iirc Steve Fisher has said that .45 1911 mags work in 10mm 1911s.

[19852+]

I’m not going to do this but am curious how and why it works. I have seen numerous reviews and demonstrations of guys successfully using 45 ACP mags in 10mm 1911s. I’m assuming the interior frame-mag dimensions are the same for both calibers but not sure about that. But I would think the follower and feed lips would be caliber specific. In addition to this curiosity (putting 10mm cartridges into 45 mags) I would wonder about 9mm and 38 super? Could someone explain the difference in the 1911 magazine dimensions for different calibers? Do manufacturers machine the frame differently to accommodate the different width cartridges? Is the space (to accept the magazine) in the grip of a 9mm 1911 smaller than that same space in. 45 ACP 1911? There is such a big difference in the size of 9mm vs 45 that the frames must be machined with matching rectangular holes. But 10mm and 45 seem close enough to work? My question is basically the larger question of: Once 1911 was expanded to other calibers, what dimensional changes were made deviating from the original drawings for the 1911 in 45ACP?

I squeezed the feed lips on a .45 mag to get it to feed .38 super. It did sort of.. I was experimenting with the idea of a 10 round .45 mag being used to create a 10+ round .38 super.

[Rmiked]

Yes, I see many examples on Utube of actually shooting successfully with 10mm ammo in 45 mags. I’m just wondering if the frames of the smaller calibers , like 9mm, are machined narrower and are those smaller caliber mags actually thinner? It’s looking like the 10mm and 45 mag thicknesses are the same. Otherwise they wouldn’t fit well.

[Evil_Ed]

A 1911 frame is a 1911 frame is a 1911 frame. The only differences are whether the feed ramp is a 45ACP feed ramp, or an "other" feed ramp (different angle/depth/etc). (or the ramp has been cut out for a ramped barrel)

You start getting caliber specific things when you get into what ejector is fitted to the frame, and how deep and at what angle the aforementioned feed ramp is cut. Or, if it's a gun with one of the ramped barrel setups, it comes down to just which ejector is in the frame. Past that, everything is in the barrel or slide.

This is why 9mm 1911s have been historically unreliable, and why that probably won't change. Shorter OAL cartridges (especially tapered ones like 9mm) do not typically do well as it was designed around feeding a straight walled chonky big boy case. 10mm and 38 Super feed well in it because they are both roughly the same length as 45ACP and straight walled.

This is why when Wilson decided to get serious about a 1911-esque gun in 9mm, they built it around a known-good magazine (the Walther P99/PPQ series).

[Bergeron]

There's enough really good 10mm magazines that I find it hard to discern a convincing argument for the use of .45 ACP magazines in my 10mms.

I don't trust the original Colt magazines. Not that I think that they're bad, but when I got my first Delta back in like 2006, I was fixed up by a much more knowledgeable and experienced 10mm 1911 shooter with a set of of the Shooting Star/Metalform magazines. I used those without issue until the latest Wilson design came out, switched to those, and have only good news to report.

I'm very interested in the Tripp CobraMags, and to see if there's any difference in performance between the 10-round "System", standard length 9-round, and extended length 10-round, but I cannot work up the energy to stuff $0.76/round into my .45 ACP mags as an experiment.

Sure, if the zombies were pounding down the windows to my house, and I was holding my favorite Colt, a .45 ACP mag, and a box of 10mm, I wouldn't hesitate, but the existing 10mm mag options are very good, so unless I had a gun built, and the smith particularly went out of his way to recommend .45 ACP mags, I never see myself even bothering to try.

[farscott]

A 1911 frame is a 1911 frame is a 1911 frame. The only differences are whether the feed ramp is a 45ACP feed ramp, or an "other" feed ramp (different angle/depth/etc). (or the ramp has been cut out for a ramped barrel)

You start getting caliber specific things when you get into what ejector is fitted to the frame, and how deep and at what angle the aforementioned feed ramp is cut. Or, if it's a gun with one of the ramped barrel setups, it comes down to just which ejector is in the frame. Past that, everything is in the barrel or slide.

This is why 9mm 1911s have been historically unreliable, and why that probably won't change. Shorter OAL cartridges (especially tapered ones like 9mm) do not typically do well as it was designed around feeding a straight walled chonky big boy case. 10mm and 38 Super feed well in it because they are both roughly the same length as 45ACP and straight walled.

This is why when Wilson decided to get serious about a 1911-esque gun in 9mm, they built it around a known-good magazine (the Walther P99/PPQ series).

Great post. About the only other comment is that the mainspring rate can be lower for 9x19 1911 IF one is not using "hard" primers. That requires less energy from the slide to cock the hammer and may make the slide travel a bit faster. Unlike many 1911-pattern guns where the slide can outrun the magazine, 9x19 1911-pattern guns have the issue that the recoil impulse is marginal at best to consistently cycle the pistol.

I always wondered why Colt created the Commander when the replacement for the 1911 was proposed. It would have made more sense from a "the more is the same, the better" to the War Department, but Colt created the shorter pistol which was not short enough to meet the War Department requirement. I believe part of the reason was reliability with the lesser impulse of the 9x19. The common story is the gun was supposed to be less than 7" long per the War Department and weigh less than 29 ounces, but the Commander is almost 7.75" long while weighing right at 29 ounces with a specially lightened slide. Colt could have shortened the slide to meet the length requirement and would not have needed to lighten the slide. Colt shortened the 1911 by only 0.75" versus the 1.5" requested by the War Department. The S&W M39, another entry, was 7.6" long.

We later learned with the Officer's ACP that a 3.5" barrel was possible. The Officer's ACP slide is 1.5" shorter than the 1911, meaning it met that War Department requirement. The Colt Defender's slide is 0.5" shorter than the Officer's ACP slide and is pretty reliable with 9x19.

[Rick R]

My 10mm SR1911 is not happy with CMC (or other brand) .45 magazines. It runs flawlessly with CMC 10MM 9 round magazines.

FWIW my 9mm Commander size SR1911 likes both CMC 10 round mags and the Brownell’s version that looks to be identical but black. I upped the OEM recoil spring from 10# to 14# and only shoot 124gr fmj or jhp +P ammo thru it. I actually trust it as much as any 5” 1911 I’ve owned and more than any prior Commander size pistol.

I believe the manufactures make specific sized magazines for a reason.