mp5 hop issues

[wadie]

i have a fully upgraded JG mp5 (apart from the hop chamber), bbs get stuck and pretty much drop out the barrel half of the time, i thought this was the R-hop installed incorrectly at first but i tried some other hop up rubbers, but that changed nothing...help guys

hops ive tried:
R-hop
prommy
lonex 70
madbull red