This is kind of long but here are the facts.
I already posted a story last week about my new upper test report. In that post I mentioned that I found some split cases and all of the fired brass was smoked up or burnt looking.
This ammo was brand new UMC 115 gr. FMJ.
After that range trip I inspected and cleaned up the chamber area, forcing cone in front of chamber and the cone area of the bolt. All these surfaces had a real heavy and gritty phosphate coating and I was concerned that it was holding the bolt back from closing completely.
I polished these surfaces by using some fine
or mild 3M Scotch-Brite wrapped around a cleaning jag and chucked in a drill to spin it.
This polished it real nice and smooth with no metal removal at all.
Also checked headspace best I could by taking a loaded round and measuring it to verify length and painted it with a black Sharpie.
Chambered with bolt (firing pin removed) and then checked that case mouth was making contact with front of chamber evenly and that bolt was not holding off seating. All looked OK.
Back out for a shoot and still had a couple split cases! Tried a differant brand of ammo, Olympic 124 gr. FMJ, for comparison.
After 20- 30 rounds I checked spent brass and found some with blown out primers! Shot couple more and POW!! had a round blow the base off and stuck the shell casing in chamber!! Funny thing was that I was holding it at waist level and watching bolt on these rounds to see if it was closing completely and it looked like it was. Talk about a scary face full of fire and metal bits! Good thing I wear glasses or I could have lost a eye!
That Olympic Greek ammo must have a thinner case or differant dimension than UMC.
OK, now its back to the house because the stuck shell casing is not coming out easily. Futher inspection shows I also now have broken firing pin! And face of bolt has primer pocket imprint!
I don't think I will be shooting this baby again until it goes back to OLYMPIC ARMS.
On a bottleneck rifle case I would say I had a oversized headspace problem from the evidence so far?
Any ideas ????????????????????