Ok, so I am running a blow back operated 9mm at around 800 rpm. Out of 150 rounds fired, 4 of them resulted in bulged cases, at the base. One, very dramatic. Looks like you tried to blow it up like a balloon.
So my question is, how would you determine if the gun is firing early (before the round is completely in the chamber) or if the bolt is extracting the case too quickly after firing?
Next, thoughts as to if it's a buffer weight issue or gas pressure issue or both.
Rounds are 124 grain hard cast over Hi Skor 700x powder.
Thoughts, ideas??
So my question is, how would you determine if the gun is firing early (before the round is completely in the chamber) or if the bolt is extracting the case too quickly after firing?
Next, thoughts as to if it's a buffer weight issue or gas pressure issue or both.
Rounds are 124 grain hard cast over Hi Skor 700x powder.
Thoughts, ideas??