Primer flow is more of a FP fit to hole issue, has very little to do with showing HP signs. This can happen at starting loads if the clearance is too great. There is one mfg of bolts for AR's I will no longer buy. They are running 0.004" clearance and you get primer flow no matter what primer you use. With today's modern CNC equipment there is reason for this. I contacted them, return the bolt and the replacement was worse yet. I moved to JP HP bolt no problems. Since, I have repaired the bolt with a bushing of proper clearance, 0.001"-0.0015".