This past weekend I went for one day to the Shooters Gauntlet MG Shoot, Stone Mountain, in PA. It is a smaller mini Knob Creek. Great Fun, they had five cars, a "tree cutting contest'. I did not have a chance to test Bobs recommendations prior to the shoot. I put in a booster cone with a larger orifice and I lubed the ammo in the belts just prior to shooting. At first it shot OK, then I was having light primer strikes and jams. I assumed that it was the larger booster hole. But in retrospect it could have been a number of things. I was using some brand new HK21 belts. This style belt had worked fine before. I had placed a small piece of rubber on the trigger guard to keep case necks from getting crushed. Perhaps the cases were hitting the rubber an bouncing back into the ejection port. At the time, I read this to be a failure to eject. During the day, I swapped back to a smaller booster hole, I changed barrels, bolts and recoil springs. To be frank, what I did and when I did it is all a blur now. This type of shooting event is not conducive to clear thinking and methodical trouble shooting.
By the end of the day, I had shot 2000 rounds, had numerous malfunctions which never occurred before and 5 cases separate. At least one case was new Factory Lake City and the others were Malaysian, This time, three were pulled off at the very base of the case. I saw other brass with signs of almost separating., One more toward the shoulder. Two stuck in the barrel, the others were pulled out when I ejected the next round that went partially into the chamber. I went to the range with 5 barrels and 5 bolts and used all barrels and three bolts.
When I got home, I retested all barrel and bolt combinations with my 7.62 Min and Max Gages. Two barrels had some bolts that closed on the Max gauge. One these barrels was one that came home with a stuck case. I had one barrel with a stuck case that gaged good with all bolts? Strange, I had tested all 5 barrels with all 5 bolts prior? Maybe I messed up?At home, I pulled the gun apart for detailed cleaning and inspection and noticed a couple of things. The nut that hold the recuperator that sits under the grip was loose. I noticed that the buffer section that the buffer spring sit over needed to be tightened back down into the buffer.
So, to keep things straight on the range, I tested and marked 3 barrels and 5 bolts with a tan paint stripe. All five bolts were tested as good in all three barrels. I found another bolt head that is good with the other two barrels and painted a red stipe on those. I decided just to swap out everything with spare parts that I had before doing some more methodical testing taking my time at my local range. I put in a new grip stick, a new buffer, spring and stock, new charging handle.
I will start with known good belts and LC, and tested barrels, if that works, I will test the Malaysian Ammo. I will go through testing all barrels and bolts, and go to larger boosters if needed? I am not sure what else to do? Any advice is appreciated.