I have a Springfield 1911 Mil spec ss 45. What do I need to change to shoot 9mm or .40. I know that the barrel needs to be changed but what else? Thanks
http://img47.imageshack.us/img47/3219/springfield45pb9151lssincaseww.jpg

spring and possibly the slide?

ok the recoil spring but the slide? what about the ejecter?

There is much more to converting the caliber of a 1911.  The slide and barrel are the two biggest factors.  Slides are configured in 3 major categories.  The .45 ACP breech face and pocket, the .40 S&W/10mm breech face and pocket, and the 9mm/.38 Super breech face and pocket.

The ejectors are wider to hit the casing properly for ejection.  The extractors are different, and the recoil springs can be different...can in the sense of you have to tune the pistol to shoot different power loads.  

One concern too that you can't forget is the frame.  Your .45 ACP feed ramp in the pistol is set up for .45.  It is deeper, wider and has a specific angle cut for the .45 round.  There is a different cut for .40/10mm and the 9mm/.38 super.

You can get away with not having to weld and recut the frame by going with a supported ramp barrel.  With a supported ramp system, you can change the entire top end and the ejector in a matter of a minute or so to a different caliber.  The only downside to this is you have to make the cuts for the supported ramp and you are dedicated to only using a supported ramp barrel for the rest of the life of the pistol.  Not that there is anything wrong with them, they are just a little more expensive in some cases.

Just passing on some info, hope it goes to good use.

Take care,
Bob

Thanks Miller_Custom_1911 that is the kind of info I was wanting to know. I guess I will just buy a new SA in 9mm or .40

Anytime.

Bob

Why?

PBIR, CEO
Society for the Prevention of Cruelty to 1911's

to convert over, you buy a new pistol. I ran the numbers a few times your only saving 100 at the most from new. And if your not a GS it will cost you more than just buying a new gun in the cal. you want.

Put in a .400 Corbon barrel an there you go.

Upper changes:  Slide, barrel, bushing and extractor

Lower changes:  Ejector and magazines.

Honestly, just guy a second or third gun, however this time buy a SV with the Interchangable Breechface system.  You can change calibers with a barrel, extractor, ejector, and replacing just the breechface.  Really neat system and it works.

Rich