Crosman seals & pump cup

[--ped--]

the UK/Can 1377 valves have the blow by hole and easily cured by threading the hole m3 and thread locking a m3 grubscrew in,some I found also had the bottom of the exhaust chamber (below port)bored to increase volumeof that area so the pressure at the pellet was reduced

[TonyL]

Thanks ped. Points noted for when I have a tinker.

If I was feeling flush at the time, I'd probably go down the complete flat too conversion, replacing pump head and valve body at the same time. But power not a requirement anyway, so maybe better just to do as above.

[--ped--]

look up about stuffing a piston and shaving the valve nose also packing the pump cup from the piston and pinning it
all diy mods that will gain power for a bit of elbow grease