1st...Why would you NOT oil the damn thing ?...run it as wet as possible.
2nd...How's the extractor...it may be worn.
3rd...Ammo. What Brand !?
Buy a few boxes of different brands and run a few of each through it...AFTER the OIL has been applied.
Model 60, about 10 years old, I have taken it apart and cleaned with brake cleaner, put back together, without any oil or lube. Looking for some guidance