The .45 ACP is a low pressure round. So I know it's not that. It's hard to specify just one thing that was the problem.
My Springfield GI needed a buffer wheel on the left frame rail. The stainless had gaulled and was grinding. The slide would hang up in the rear position. After it was fixed, it was the most accurate gun I had purchased at the time. It would not feed hollow points though and reliability was iffy. So I tuned and tweaked the magazines.
My next handgun purchase was a Ruger P97. It was VERY reliable. The accuracy was great, and the sights worked better for me. It fed FMJs and HPs and all 6 of my magazines for it needed NO tweaking.
I then had an opportunity to trade off my GI stainless for a Loaded Stainless. Not too much cash was involved, so I did it.
It was TIGHT. Gaulling was terrible. The slide ceased up while shooting it. The gun shop owner orders a new one for me and receives an rma on that one.
New one comes in a couple days later. Greased all the parts that mated together and worked the slide about 1000 times until it would move freely without sticking. Put CLP in it and ran a 50 round box trouble free. Purchased extra mags for it and they ALL needed fitting to run right!
Eventually sold the P97 to a friend who was getting into guns. He loved it.
My next .45 would be a Ruger... SR1911
This is how they should be done! Not so damn tight It would not work. Correctly machined internals, everything ran fine, except... Some of the mags I tweaked for the Springers needed to be REtweaked for the SR1911. Found out about how bad the rust issue could get on these. I'll look for the thread I had pics posted in. It was BAD. But I do miss my Ruger 45s. sometimes...
I still haven't had a chance to shoot the RIA, but it seems smoother than the other 1911s I have owned. A buddy of mine keeps drooling all over it, but I think I'm gonna keep this one!
My next .45 may actually be a Sig P220 instead of a 1911... I have seen them go toe-to-toe against 1911s in the accuracy dept. AND if it's as reliable as my P226, I have a clear winner.