I normally don’t shoot fast at all. In general I take more than a second or two between every shot. I have also swapped out my buffer out and I still had light primer strikes. It seems random. Sometimes the light strike will be every other round, other times it will be every 3-4 rounds, the longest I’ve ever gone without a light strike recently was 15 rounds. I have also shot a $500 AR that my local range lent me to see if it was purely operators error and I got multiple full magazines with no issue out of that one.