Yeah, dunno if anyone already posted this, but I think I figured out why the CA 249 box mag jams so much.
Sorry the pictures are so blurry, my camera is crap for close up shots.
http://img.photobucket.com/albums/v6...a249mag003.jpg <-- real jam
http://img.photobucket.com/albums/v6...a249mag006.jpg <-- This picture is a mockup of what looks like what happens from that angle.
Basically it just looks like a case of bad designing. What'd normally happen is that the really small wheel you see slightly on the left is moveable and guides the BBs into the wheel and tunnel where they feed normally. However if the BBs get pressed in a certain way two BBs lodge themselves between the feed wheel and the guide wheel.
I've repeated the test a couple times and can confirm this does happen repeatidly **setting up a continuous feed of BBs, it'll jam in a few hundred BBs**
As if this moment I'm not sure how to correct it. I'll give a crack at it thursday when I'm bored... but just letting everyone else that cares know.