And if you don't have the original spring, you can guesstimate how long to cut your replacement by using the counterbored bolt in the trigger plate as a gauge. Run the bolt in until the trip can't be depressed enuf to close the gun. Amount of bolt protruding above the trigger plate plus depth of cntrbore is the amount to trim the spring. You do want it move the trip authoritatively but you can't have more coils than there's room for.

jack