Been a while but I would normally run an 11 to 14 pound spring with my bullseye guns. They used a similar 185 grain SWC but with 3.9grs of Alliant Bullseye powder. As recommended above, buy a set of various weights and test them out to find what best works with your load/gun and to some extent how you grip the piece while firing. Good luck.
NRA Life Member
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