I just replaced my stock RH spring with a 12# from the Brownells kit. I did the polishing, buffing, etc work from IOWEGAN'S Gun Guide. In his guide, he suggests taking 0.020" off the top hammer step in order to avoid light hammer strikes with the new lighter spring. He has lots of pictures and diagrams for you to follow so you don't screw up.
His Gun Guide is a must to have for you double-action types.
I just finished my gun. Haven't been to the range yet.
Here's your link for a "necessary" manual.
http://rugerforum.net/miscellaneous/188 ... guide.html
Here is my stock hammer and my caliper reading. The top hammer step is that metal portion of the hammer on the top left of hammer. When you remove some of this, you must maintain same "angle" of hammer step so that finished work will fit "snugly" or flush against the frame. You can check your work periodically by inserting the hammer into the frame and using the hammer pivot pin to check the "flushness of fit."
This removal of metal allows more energy to be transferred to the firing pin, rather than "wasted" against the frame.
Of course, the Gun Guide discusses this in detail with lots of drawings.
And this is the tracing I made of the above setup
BEFORE I began to remove metal. Use a tracing to make sure you are maintaining the proper angle. Note that the top hammer step doesn't start out being "square" to the rest of the hammer. As you can see, when I finished, I had removed 0.017" instead of 0.020". There are many ways to remove this metal. From milling machine to files. Good luck. When you're done, you will realize you had fun.
Many thanks to IOWEGAN for his Guide and my apologies for the temporary use of his brain-power to help out another Ruger-ite.
And while you're "in there,"
measure the protrusion of your firing pin through the recoil shield. Mine measured 0.055." You should have about 0.050" at least. My stock RH had zero light primer hits.
Sonnytoo
