Rem. 1187 bolt doesn't fully close.
Trying to fix a friends gun. Rem. 1187 premier skeet, Intermittently the bolt stops about 1/4" short of closing, if you hit the operating handle with the heal of you hand it will close. He had a gun smith look at it he replaced the action spring, not fixed. The gun is spotlessly cleaned a few times even sonic cleaned trig. assy. Put in a brand new bolt carrier, worked perfect for about 350-400 rounds. Back to same problem. Changed bolt carrier again from a know working gun, same problem. List of parts changed Action spring, bolt carrier 3X's, Bolt assy. 3X's, trigger group 3X's. Work done changed parts above, inspect everything I could think of, found some rough metal here and there some high spots but nothing out of the ordinary. But I stoned everything out and smooth them buff polished with a Dremel and compound. It's not ammo cause we have tried numerous reloads as well as AA's STS's and four other factory loads. I'm stumped!! Anybody with anything similar or Ideas ???