On my target action(SA), I measured(rather crudely) the spring rate at 18.3#/in. It's made from .055 wire. The calculated energy is 102.3 in.-oz. and lock time is 1.9 msec. I made a new spring with the same size and number of coils out of .051 wire. It's rate measured at 14.5#/in. Calculated energy dropped to 80 in.-oz. and locktime increased to 2.1 msec. Bolt lift eased significantly . I have not had a chance to shoot it yet.

RWO