Are you using the Norc ammo? I've found that some of the 45acp rounds were gritty and some even corroded a bit. It will sometimes cause an occasional feeding problem, even in my STI 1911's. I just give the casings a wipe and they feed fine afterwords. Also, that Norinco ammo is great, but pretty dirty. After 200 rounds, the chamber can get pretty dirty and can sometimes give you a similar feeding problem.
But what has been said in prior posts is 100% correct. You want to "slingshot" that slide to get a consistent feed. My Norc 1911's and STI's are well broken in now, but if I did ease the slide in, I'm sure I would have a similar feed problem.