Hmmm... not too bad!
Just a few points for you to note:
1) The items need to be beter arranged - I couldn't see half of the mags and the rest was somewhat haphazardly placed at best.
2) Different loading sequence. God, that gun got so damned annoying, firing off again, and again, and again, and again... @_@
Other than that, not bad - would be cool if there was some way to save the gun you made, but I dunno if Flash can do that sorta shizzle.