On another board someone said he was able fit a 10MM slide onto an M1911 and with the proper barrel and magazine fire it and he implied you could fit a 9MM or 38 Super and fire it. My understanding of the M1911 is that it is the position of the ejector-which on mine are machined into the frame-which determines what rounds you can fire and only rounds that have the same case head size-i.e. 9MM and 38 Super-can be interchanged.
Caliber changes in an M1911
- Thread starter SIGSHR
- Start date
Aguila Blanca
Staff
Your sentence is in conflict with itself. First you say it's the ejector that controls, but then you mention different case head size. Both statements are partially correct ... sort of.SIGSHR said:
Slides: In general, 1911s use three breech face cuts, one for .45 ACP, one for .40 S&W and 10mm, and one for 9mm and .38 Super. BUT ... I have it on good authority that Para-Ordnance used the same breech face cut for 9mm, .38 Super, .40 S&W, and 10mm. That was tested for me by a friend who owns a Para P18.9 -- he was able to fit a .40 S&W case into his slide. End of discussion. Nonetheless, it's better to stick with the three groupings I initially spelled out.
Ejectors: The position of the ejector is always the same, meaning that the positions of the two holes in the frame are always drilled in the exact same locations. However, 9mm and .38 Super ejectors are thicker than .45 ACP ejectors, and the extra material is added on the side toward the centerline of the pistol. These ejectors have a visible step in the surface facing the centerline. The offset brings the nose of the ejector closer to the centerline, to allow for the smaller case head. I don't know which type is "right" for .40 S&W and 10mm. It may well be the both types will work. IIRC, all Para-Ordnance ejectors were the offset style, even on their .45 ACP pistols.
I have never heard of a 1911 with the ejector machined as an integral part of the frame.
Feed ramp: You didn't mention the feed ramp. The feed ramp on 9mm 1911s is cut to a different angle than on .45s, and it's set slightly farther to the rear of the pistol. It is possible to convert from .45 to 9mm, but it's sometimes tricky, and not always successful.
IF you are swapping the whole top end (slide assy with all parts +barrel) the breech face will be the "right" size for the caliber chosen.
the ejector will be in the same place (naturally) but different sizes (lengths) are used for different calibers. The "wrong" one will create functioning issues.
The original ejector is press fitted into the frame (at least Colt and the GI guns did that). Replacement ejectors require drilling a hole in the frame (if not already there) and use a cross pin to ensure being retained in place.
the ejector will be in the same place (naturally) but different sizes (lengths) are used for different calibers. The "wrong" one will create functioning issues.
The original ejector is press fitted into the frame (at least Colt and the GI guns did that). Replacement ejectors require drilling a hole in the frame (if not already there) and use a cross pin to ensure being retained in place.
With respect to the ejectors, the 45 Government Model uses one size (width), and everything else (9mm, 38 Super, 10 mm, 40 S&W, and 45 Commanders and Compact) uses another size (width). This is completely independent from whether the ejector is elongated or not.
The difference is in the ejector cut in the slide. The 45 Government Model ejector cut is a little more lateral, and everything else is a little more to the centerline. If you have a 9mm/38Su/40/10mm or 45 commander/compact ejector in place, the 45 Government Model slide won't fit on the frame. The slide will hit the ejector because the ejector is too close to the midline.
That's why the firing pin stop is different for the 45 Government Model versus everything else, too.
I built a multi-caliber single stack with a Caspian frame and 2 slides (45 and 38 Super). I asked Caspian to cut the ejector slot in the 45 (Government Model) slide so it would fit a standard 45 Government Model ejector AND a 38 Super ejector. That way I could put ANY SLIDE on it without having to change ejectors.
The difference is in the ejector cut in the slide. The 45 Government Model ejector cut is a little more lateral, and everything else is a little more to the centerline. If you have a 9mm/38Su/40/10mm or 45 commander/compact ejector in place, the 45 Government Model slide won't fit on the frame. The slide will hit the ejector because the ejector is too close to the midline.
That's why the firing pin stop is different for the 45 Government Model versus everything else, too.
I built a multi-caliber single stack with a Caspian frame and 2 slides (45 and 38 Super). I asked Caspian to cut the ejector slot in the 45 (Government Model) slide so it would fit a standard 45 Government Model ejector AND a 38 Super ejector. That way I could put ANY SLIDE on it without having to change ejectors.
The breechface and the frame feedramp are the concerns.
In the past, distant past, 1911s had breechfaces specific to each caliber.
Since some are not too far from each other - 9mm from .38 Super, Super from .40/10mm - most manufacturers have a breechface for .45, one for .40/10 and Super, or one for 9mm/Super, and the extractor is expected to take up the slack.
If you use ramped barrels, then the frame feedramp doesn't matter.
1911 ejectors are pinned into the frame in the same location, regardless of caliber, but thicker ejectors are used for calibers smaller than .45.
Colt Commanders use the thicker ejector regardless of caliber, so a slide with the 9mm/Super/.40/10mm ejector cut will work for any caliber, width-wise, but the length of the ejector is also a concern, with 9mm often being so long it won't allow ejection of live rounds in other calibers.
In the past, distant past, 1911s had breechfaces specific to each caliber.
Since some are not too far from each other - 9mm from .38 Super, Super from .40/10mm - most manufacturers have a breechface for .45, one for .40/10 and Super, or one for 9mm/Super, and the extractor is expected to take up the slack.
If you use ramped barrels, then the frame feedramp doesn't matter.
1911 ejectors are pinned into the frame in the same location, regardless of caliber, but thicker ejectors are used for calibers smaller than .45.
Colt Commanders use the thicker ejector regardless of caliber, so a slide with the 9mm/Super/.40/10mm ejector cut will work for any caliber, width-wise, but the length of the ejector is also a concern, with 9mm often being so long it won't allow ejection of live rounds in other calibers.
I'd use just a little bit of caution going into a 1911 project using an AMT frame.
It might go smooth,but my first 1911 38 Super was built on an AMT frame I bought at the LGS maybe in the 80's.
AMT did not get their reverse engineering just right...maybe casting shrink was a factor.. Be real careful with your mag catch.On mine,a standard 1911 won't work.
Remember the 38 Super is semi-rimmed. That makes for a slightly larger breech face....and there is not that much difference between a 38Super and 40 S+W / 10 mm rim diameter .
My Colt brand 38 Super slide easily accepts 10 mm brass in the breech face.
To be fair,I have not built a 40 or 10 mm,so I don't know if more clearance would be necessary at the breech.
It might go smooth,but my first 1911 38 Super was built on an AMT frame I bought at the LGS maybe in the 80's.
AMT did not get their reverse engineering just right...maybe casting shrink was a factor.. Be real careful with your mag catch.On mine,a standard 1911 won't work.
Remember the 38 Super is semi-rimmed. That makes for a slightly larger breech face....and there is not that much difference between a 38Super and 40 S+W / 10 mm rim diameter .
My Colt brand 38 Super slide easily accepts 10 mm brass in the breech face.
To be fair,I have not built a 40 or 10 mm,so I don't know if more clearance would be necessary at the breech.