Calculated pressure provided at that much force produces values in the 300 to 500 psi range. The math is right, and I agree with the piston diameter measurement. The spring compression stock must not be anywhere near that. It should be possible to work out the stock spring compressed length in a non-adjustable regulator very easily. Measure the free standing length of a known spring, say the 30 psi spring, and enter it into the spreadsheet free length. I'll use the result in another spreadsheet I've made for a handy TBI spring helper.
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