TM Recoil Jammed

[LSUK]

Hey everyone!

Got a question regarding my TM HK416D Custom. During a game day a few weeks back my recoil weight stopped working. Initially i thought the weight might be jammed but it doesn't seem to be the case. The gun still fires but the recoil part doesn't work currently and i don't want to potentially put un-necessary wear on anything without having it working normally. 
Anyone got any ideas what could be causing the problem? I have taken the bufffer tube off and checked the the recoil weight still works and it seems fine, spring is fine and piston seems fine too. Just for some reason it doesn't want to push the recoil weight back?

Note: No idea how to actually access the recoil weight itself as i'm not entirely sure how to take the end off the buffer tube...
Any assistance would be much appreciated. ?

Thanks all!

 

[mightyjebus]

chances are the block on the back of the piston that drives the recoil weight back has snapped off. take the front pin out and seperate the upper from the lower. on top of the gearbox you will see a little hook that goes inside the gearbox and catches the piston as it travels back. if the piston has snapped then you should find the broken bit rattling around inside the gearbox

 

[LSUK]

chances are the block on the back of the piston that drives the recoil weight back has snapped off. take the front pin out and seperate the upper from the lower. on top of the gearbox you will see a little hook that goes inside the gearbox and catches the piston as it travels back. if the piston has snapped then you should find the broken bit rattling around inside the gearbox

Thanks for the info... took the gun apart completely to have a good look into it.

Turns out the teeth on the piston had been shredded to the point where it wasn't pushing back enough to make contact with the recoil piston. Would still fire (at like 200fps less than usual lol) and after grabbing a chrono i did some testing. Replaced the piston, did some TLC to the internals (mainly consisting of cleaning out all the plastic shavings which were scattered through the gearbox ?) - all working now. Thanks for the info anyway!