Need a Flat Top.

[Petey]

I need a flat top piston for a Crosman 140/1400.  just picked up another 140 and want to do something different this time.
Any information would be greatly appreciated.

Thank you,
Pete.

[rsterne]

AFAIK, they are not a commercially available item.... I use a lathe and turn off the rubber seal and the brass retainer (it's pressed on).... being very careful to not damage the aluminum rod inside the brass.... I take a piece of 5/8" aluminum rod, drill it in a lathe to 5/16", and sand it a couple thou inside.... You want it a press fit on the old piston.... I leave the felt wiper in place and press the sleeve on until it bottoms on the shoulder on the piston.... Then I chuck the pump rod in the lathe and turn the outside to the proper OD (about 0.010" under tube size) and face it off flush with the end of the piston.... I then machine in an O-ring groove leaving only about 0.030" between the groove and the end of the new piston....

Bob

[Petey]

Thanks Bob.
I need to learn some machining skills.  A drill and a file are not enough for this hobby. Lol