My appraisal of this problem would be to first look at the firing pin and see if it is a good candidate for a spring cutting. It should be of the smaller in diameter type rather than the type used in older guns that generaly tended to be larger in diameter. Secondly check the firing pin protrusion to make sure you have a nice clean and easy pin movement out to at least the required 3/32" protrusion. Then fire a few rounds to check the primer indentations are nice and pronounced. If all this checks out, I would disassemble the hammer drive and start with one coil cut off. reassemble and test fire to compare the new indent. If no noticable change in indentation has acured, take 1/2 coil off and test fire again. You should start to see a noticable easier hammer cocking tension hopefully before you see a lighter dent in the primer. Easy does it. Its equaly if not more important to see your son move the hammer nice and slowly off full cock to at rest possition. Good spring tuneing and much practice on your son's part will get you guys in the feild safely!
