CA mp5a5 weird muffling when fired
 

i was just firing my aeg in the yard and after afew shots it began to start making a weird sound when fired almost like it under water =s never heard it make this noise before either.. and lately it seems like my hop up isn't tuning correctly either.. any ideas?

Was it still firing BB's? When it makes that sound it's probably not and is jamming up. Something wrong with your hopup unit or rubber. Take it to a gundoc.

no its was not jammed and yeah i am going to be doing that

Sounds like the piston head might have come off from the piston, or the rubber has come off the cylinder head. I have had both these happen and they make a really funny farting noise. Either way, you will prob have to open up the gearbox