best way to get pts epm's pts epm's in cyma sr25

im in search of the best mags that song explode on me and feed flawlessly in a cyma sr25. what seems to happen iwht a couple of my syma mags is a bb will get between the sin and follower and cause a jamand when i take it apart themag explodes on me cand gets tangles and they are a bitch to untangle. battleaxe 220rd mags dont feed well in my sr25. i know pts is supposed to be good i tried filing but it doesn't drop free and i need to argue with it to get it out. i did try filing and that had minina effect. so what's the best way to get them to fit since filing had minimal effect