Last thing to do on this rifle was replace the pump cup.
The rubber seal itself is the same OD as a modern Benjamin 392/397 so just a simple matter of popping the old one out and popping a new one in.......
WRONG!
The bright lights at Sheridan decided to crimp the rubber seal into the steel cup with the most complicated crimping die I have ever seen.
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So a new cup had to be made to accommodate the pop in seal. I could have made it out of anything really but I chose brass.
Turn down stock to 0.765 OD
Drill a center hole with a #3 drill (tap drill for 1/4"-28)
Hollow the center of the cup to 0.600" ID to a depth of .250"
then create a lip to hold the rubber seal by opening up the ID of the cup to 0.640" out to within 0.025" of the edge.
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Part the piece off at .400" thick and then tap the remainder of the #3 hole to 1/4"-28. Then face it off to 0.375"
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Install the cup and button it up.
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