When I release the bolt catch and the ammo tries to go into battery, it gets jammed
The ammo will not fully get into the chamber and the bolt can't lock in.  I have to pull back the charger and let it slam back in several times to get the bolt to lock in.  It will jam after 2 or 3 shots too.
Is it the mag?
What should I do?
Please help

Bend the feed lips on the mag a little more open at the front edge of them.  Also clean the chamber well and make sure there is no burrs at the barrel extension/feed ramp.  My Beowulf wore out the stock mag spring within 100 rounds.  I now use 20 rounder and I add the Wolff +10% XP springs and open up the feed lips a little.  Reliability now is 100%.  

I also removed my barrel from the upper receiver and polished the feed ramp of the barrel extension to a like chrome appearance.  I added a Wolff XP M4 extractor spring as well.

thanks

mine runs 2x buffer spring and mags with wolff + springs