I have a brand new G&G SRXL which I immediately shimmed perfectly and installed a deans plug on. However now the only problem with it is the stock is loose and as I tighten the screw the gearbox locks up due to the spring guide, I don't like how loose it is with the current screw. What would fix this problem? I'v tried washers on the screw but still ended up to only lock the gearbox and I'v also tried shimming the buffer tube to the gun to only lock it up again. (when I say locked up I mean my Matrix 3000 High torque motor and 9.6v NIMH battery cannot cycle the gearbox, but when I loosen it it fully cycles again) Would a ball barring spring guide/piston head fix this? please help.