I just finished my first build and tried to test it, and it will not pull the rounds off the mag. It only puts a dent on the casing or scrape marks. I've tried 3 different mags. Magpul, CMMG, and DPMS with the same results. Any one have ideas on what's going on? Could it be related to the bolt barely catching on the bolt catch? The bolt releases when I eject the mag (haven't figured that one out yet too).