If the parts wont drop into a Colt or GI gun, then its probably a good indication the parts arent to spec, or at least, the correct specs I always had the best luck with. My Colt and GI guns were the only ones I ever trusted to carry, and that was only about 10 guns out of 40.
Unfortunately, even the later Colts were not all that great, with their plastic parts and all. But they still seemed to work without issue.
Everything else were just copies of varying quality (names really mean nothing here) and company specific specs, that very often, were trouble from the giddy up.
Early Springfields were pretty much Colt/GI. Later guns (my last were late 90's guns) flat out sucked. Kimber was right there with the later Springfields (same era). Had a couple of home builds too that were aggravating. Seems most of the home builds Ive had of any type, AR, AK, FAL, 1911, etc, were trouble. The main reason I wont buy another. Learned my lesson, it just took awhile.