5 inch standard size 1911- Government
What parts can you buy, and with good confidence know they will fit into your 1911 without modification. ie Firing Pin, grips, Springs, barrel .B bushing…
And what parts will almost certainly need work? Mainspring Housing-magwell…
Grips, springs, firing pin, and magazine release are about it. Anything else needs to be properly fit.
Grips are about the only thing that you might be able to swap out without much trouble. Even with grips you might have to do some sanding to get them to fit. Everything else it’s almost guarenteed you’ll have to do some sort of fitting. Not all 1911’s are drilled for a standard firing pin. Caspian slides for instance are drilled for .38 Super/9mm pins, even though it might be a .45 slide. I’ve yet to see a firing pin stop that will just fit right in. There are “drop in” barrels, but they usually come with a warning some fitting may still be required.
Grips are about the only thing. Magazine releases can even be tricky.
Almost everything will require fitting of some sort. mainspring housings SHOULD be standard, but it’s hard to tell.
A smarter man then myself once said that “Drop-in does not exist in the world of the 1911.”
I have built a complete gun from “drop-in” parts. The only item that needed fitting was the thumb safety. It was not the tightest 1911 but it functioned well. I did polish the feed ramp on the frame and opened/polished the barrel chamber mouth for better feeding.
As far as parts - a GI mil-spec gun should be able to accept most parts with out fitting. Not mil-spec are another beast. Everything can be difficult.
Grip screws.
That has been my experience. For a true “milspec” pistol, most things will drop in but a lot of companies have made small changes which will affect how the parts fit.
Throw in bushingless barrels, 38 super firing pins, as well as series 80/Schwartz firing pin safeties and things don’t always go together.
Unless you have a Norinco or a 1911 with “slim” grips 
Thats pretty much what I was afraid of, NADA! Zilch. Even my grips are coming a little losse, even with the scews fastened down. My Brown has a scootch of play in one of the grips. And my TRP does as well, but I changed those grips from factory grips on the trp. Does the grip get sloppy at the hole or what gives?
Irritating :mad:
Check to make sure the grip bushings are properly staked as they can cause problems with grip panels coming loose.