Hi, so like I said, my gun is brand new ( home made )...It's a M4...Here's my problem...When I try to shoot, my gun doesn't...Pretty simple right ?

...My gearbox runs without any problem...When I put a single BB into the hopup "chamber" ( directly in front of the nozzle ), it shoots without any problem...
But when I put a mag on and I pull the trigger,nothing happens...the gearbox does its cycle, but no BBs leave the barrel and no BBs go in front of the nozzle...
Mag problem ? Nozzle problem ?...HALP !

...
thk,
Per