[Flatlander]

Like Vince, I too had to break in my brand new KA m4 mags. All I do though is put about 3 drops of silicon oil into the feed tube then load the mag up with BB's (to help spread the oil). The spring/follower/BB's may be getting caught or slowed down inside the channels. Before you oil it, load up the mag with some BB's and pull the feed lip back and let them fly out. They should come out with quite a bit of force and not just dribble out. Do the oiling technique I mentioned above and see if they come shooting out better. I also had to file down the feed lips on some of my KA mags to get them to feed properly. I've also heard that is a problem on their m14 mags.

If that doesn't work, try a few drops of oil inside the hopup via the magwell.