it *could* be that your spring may have jumped out of the piston fouling it up. if this is the case, the farting noise may have been the sear catching on the spring.
if it wont go forward at all you may have to pull the spring guide stopper, but please do this carefully as the cylinder may shoot forward.
from what little i know about clipping sniper springs, most of what i have read has been on M170'ish springs. But if i am honest i am not that knowledgeable on sniper spring clipping etc.