Im gonna guess it shoots say 275fps on 0.20's
Check for a torn/ripped/perished bucking first
pi$$ poor seals and weak spring that faded after being stored pre-cocked
buy a m105 spring is likely the response and a bit of service inside
think the G&G piston head is crap tbh
think you might want a new spring & likely this....
https://www.amazon.co.uk/SHS-Tooth-Piston-TT0081-Airsoft/dp/B018KJUQQ0
Normally I wouldn't recommend an alloy head but that combo is da nutz
SHS pistons often are bit tight in some boxes - but not in G&G's
That head though heavy is awesome, seriously if you don't get good~great compression then the o-ring is missing
could drop the bearings inside to save some weight (I would - use the G&G 5mm piston spacer)
but best put a bit of thread lock on the screw to be safe
m100 spring or element m105
ptfe tape on cylinder head, correct AoE
yup reckon that will fix it up quite nicely quite cheaply & easily
