I have an Eagle Arms M-15A2 that will not feed the first rounds out of a 20 rnd mag. It also will only feed 20 or so rounds out of a 30 rnd mag. This happens on several mags of different makes so I'm sure it's not a mag problem. I haven't fired this rifle that much. Is it possible that the spring pushing the bolt forward may not have enough arse to strip the first few rounds?
BTW; This rifle says Eagle Arms by Armalite on the receiver. What is the story on Eagle Arms and what's the difference between Eagle and Armalite.
The first thing to do is make sure only putting 20 rounds in the 20 round mags. They were designed with plenty of room to compress when inserting a full magazine into the weapon while the bolt is closed but the extra room makes it possible to squeeze a 21st round in there which will often not feed correctly.
If the recoil spring was too weak to strip the rounds off the mag then you'd have problems with the first rounds out of a 30 when the tension is higher, not the last 10 rounds.
When it doesn't feed, what exactly is happening? Is it getting a round partway out of the mag but hanging up along the way? Cycling fully but not loading a fresh round?
About Eagle and Armalite: The Armalite division of Fairchaild that introduced the AR15 way back when went away long ago. Eagle was a completely different company and had been making ARs for several years and they bought the rights to the Armalite name and began producing weapons under that name. They kept the Eagle name around and use it on their more basic budget rifles.