Thanks for all the advice guys. I'm going to start with the pelgun oil on the mag and see if that helps and then try the full strip down. Strange though that it worked for about 5-6 mags perfectly before it started jamming. I somehow have the feeling that the bolt isn't coming forward with enough force to engage/extract the bb on it's way forward, as tthat's appears to be around the point it's stopping on its forward travel.