CUSTOM FLAT-TOP PISTON for Crosman 1377, 1322, 1300KT, 2289G, PC77, Drifter

Description

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This is the Magnum Airpower flat-faced (AKA flat-top) adjustable piston and custom piston pin.
To use this piston you need a flat-faced (AKA flat-top) valve or cut the cone off of your factory valve, we have complete valve and piston kits listed if you need both parts, the valves are custom-machined from 7075-T6 aluminum.
This double-seal piston design stays lubricated better than single-seal pistons by retaining oil between the seals and pushing it back and forth with each pump. The pin is machined from tool steel with radiused ends to match the internal tube contour, this reduces scoring inside the tube. The piston base is machined from Delrin for ultra-smooth pumping and to function as a compression buffer to help protect metal parts from excessive stress. The piston rides on the Delrin base and o-rings with no metal-to-metal contact to reduce wear.
It produces more power at up to 10 or 11 pumps but falls behind our adjustable cup-seal version in the 12-17 pump range. It produces extremely tight shot to shot consistency generally within 2-3 FPS which is as good as it gets for any airgun type and works exceptionally well for precision shooting. To maintain the best possible performance, occasional piston adjustment and piston seal replacement is required, the piston seals will need replacement more often if used in dusty or dirty environments. Extra o-rings are included, 4 soft 70D which are easier to install/remove, work better in cold temps but wear faster and 4 hard 90D which work better in warm temps, wear slower but are much harder to remove from the piston head.
We also have a cup-seal version listed that is better suited for dirty/dusty environments and long-term use without having to adjust the piston or change the piston seal as often. Cup seals generally last a decade or longer even with daily use and the piston, if adjusted correctly, generally doesn't need to be adjusted again for years if ever. It produces slightly more overall power in the 12-17 pump range but slightly less power than the flat-top version at lower pump counts. It's almost as consistent as the flat-top version, generally within 5 FPS from shot to shot.
We also have complete custom valve and piston kits listed in both flat-face and cup-seal versions.