I currently own a G4 and I decided to get a bit of extra distance out of it. I took out the stock barrel, bucking and nub and replaced it with a Lonex inner barrel and a flat hop mod (Modify Baton Ryusoku Flat Hop - Hard)
It worked great at home, then the next day at a skirmish, it stopped feeding. Mid and high caps. Tried my mags in my Tavor, works great. So it's not the mags. I checked and the magazines connect with the feed tube. It will shoot one or two, then dry fire. There are no tears in the bucking, even put the other bucking and nub in (Bought two sets of the flat hop) and it has the same problems. I'm 95% sure I'm reassembling it all right.
I put the old barrel, bucking and nub in and it works great. My thing is now I lack that extra 90 feet of range that I so loved with my upgrades. But what are the new upgrades doing that makes it not feed right? Using Elite Force .25s.