I had a bunch of swivel links to tighten up the lockup, but no longer have them. They were available in .001" increments, IIRC.
My cobbled together .45ACP 1911 with Wilson barrel and collet that originally started out as a .38 Super, would make 1 1/2" to 2" groups at 50yards from a rest.

Lots of things can be done to a 1911 to improve accuracy.