just purchased todat took it home opened the box heard a rattling sound? well the nut had came loose on the loop for the tach sling, well i thought easy fix so i unscrewed one side of the stock end cap easily came off now for the other, used multitool suggested and it wont unscrew and i ended up stripping the head on a brand new out of the box gun what do i do people????thanks for all feedback help!

also what size screw is it? and what type of screw do i replace with? thanks

no i tried any other suggestions?

u where right great job it was very tight though looked at the exploded diagram and it was a push pin. how confusing though why not put a round head there in its place, thanks and good lookin out, not so happy my second gsg coming apart but very minor hope this is not a bad sign about the weapon. will run rounds through it as soon as possible, hope it does as well as my gsg-5.