I just got back from shooting my Core 15 AR and sighting in my Strikefire. I had only previously put around 15 rds through it with no problems. Today however I had three light primer strikes. I was inserting the mag, stripping one round off and then dropping it, so I could set the rifle down on a rest to shoot when it happened on all three occasions. If I ran a mag continuously I had no problems. I'm thinking I wasn't being "aggressive" enough when stripping the rounds, and maybe the bolt wasn't seating completely. I haven't taken the rifle down yet to take a look, but wanted to get some input.