M249 Drum reliability

[Giant Slayer]

Okay, so, for the past couple of games my drum on my CA M249 SAW continually jams/doesn't feed. I have found that if I pull and jiggle the bb feed tube thing, it'll unjam it somehow. I took the whole drum apart Friday and cleaned it, and only used elite force bbs in it Saturday. When I took it apart I noticed that the gearbox shell was too tight, and thus made it more difficult to feed bbs. I tightened it snuggly when I put it back together. It feeds better,but still jams. It's very frustrating trying to play airsoft when the drum doesn't feed literally half of the time.
Is there any way to make the drum more reliable? If drums are always going to be this unreliable, then the gun isn't worth fielding. Yeah, I can use highcaps in it, but I can use highcaps in an M4 that weighs half as much. Or are Classic Army drums just that sucky?

[Rev]

They are really picky with bbs, I have found G&G to work the best with box mags.

[Giant Slayer]

See, I've tried G&G bbs, and they jam just as much.

[rusty65]

Posted this in another thread. I found this to work well when I had an M249.

http://www.air-sharp.com/m249feed.htm

[Seal Team 2]

If that did not work I have another fix for it that you can use Feel free to contact me here or personally at Techtom44004@gmail.com I iwll give you the details on the fix I have done and mine never ever ver jams at all.