Reply To: The Crosman Powermaster 760…Recapturing my youth !

Forums Springers, Pumpers, C02, & Vintage The Crosman Powermaster 760…Recapturing my youth ! Reply To: The Crosman Powermaster 760…Recapturing my youth !

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GoldenStateAIRGUNer
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Kind of a hassle to disassemble the gun everytime you do a bolt modification. Wonder if epoxy ( like JB Weld) built up on the bolt and then lathe turned would work ? Only 17 fps gain on 10 pumps is minuscule. The highest velocity I hit was with 12 pumps @ 670 fps. I have found that velocity consistancy suffers dramatically at 10 pumps. One shot might to 645 and the next was 615 fps. I think I know why. When the pressure in the storage receiver is high there is a battle between the pressure built up in the compression stroke cycle and the storage receiver. The check valve begins to open during the pump stroke and causes the PSI in the pump cylinder to drop. At some point the stored pressure exceeds the compression chamber pressure causing a loss of stored air. I only notice this at 9-10 pumps. At 3-4 pumps the compressed air is always much higher than the stored pressure so it's not a issue. My 3 pump velocities only vary 5-8 fps. Just a theory on my part but it makes sense.