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RickB · March 7, 2013, 06:25 PM

Yeah, the only differences between a 1911 in .45 and one in 10mm are the barrel, magazine, slide, frame, extractor, ejector, firing pin . . .
The main problem is the breechface, which varies with chambering. A lot of .40s on the market share a slide with the same company's .38 Super, or the Super shares with 9mm, as the dimensions are not too different, but .40 to .45 is too big a difference to allow one slide to work for both calibers.
SVI makes slides with interchangeable breechface inserts, allowing one slide to work for multiple chamberings. Big bucks.
Even if you got a complete 10mm top end, you'd still have a frame with a .45-specific feed ramp cut in it; the feed ramp is also somewhat caliber-specific. You might be able to make the frame work for both calibers, but you could get around that by using ramped barrels for both calibers. The barrel ramp replaced the ramp in the frame, so you're not trying to get one ramp to work for multiple calibers.

March 7, 2013, 06:25 PM	#7
RickB Senior Member Join Date: March 1, 2000 Location: Boise, ID Posts: 8,518	Yeah, the only differences between a 1911 in .45 and one in 10mm are the barrel, magazine, slide, frame, extractor, ejector, firing pin . . . The main problem is the breechface, which varies with chambering. A lot of .40s on the market share a slide with the same company's .38 Super, or the Super shares with 9mm, as the dimensions are not too different, but .40 to .45 is too big a difference to allow one slide to work for both calibers. SVI makes slides with interchangeable breechface inserts, allowing one slide to work for multiple chamberings. Big bucks. Even if you got a complete 10mm top end, you'd still have a frame with a .45-specific feed ramp cut in it; the feed ramp is also somewhat caliber-specific. You might be able to make the frame work for both calibers, but you could get around that by using ramped barrels for both calibers. The barrel ramp replaced the ramp in the frame, so you're not trying to get one ramp to work for multiple calibers.