I originally changed the hammer spring tension by putting a small slug between the hammer and spring. To change tension I would have to disassemble the gun, remove the hammer-spring assembly and try different thickness slugs. I decided to make an adjustable setup, and this is what I came up with. You still have to remove the stock, but the turn of an allen wrench gets it adjusted. The range of adjustment is up to 0.265 inches before the hammer can't get back far enough for the sear to catch it. This is 8-1/2 turns of the set screw. For my particular needs, 4-1/2 turns turned out to be what I needed, 0.140" of spring compression. Anyway, here are some pictures and a sketch with dimensions if anyone wants to play with the idea; play at your own risk. The good thing about this mod is there are no alterations to the gun, and it can be put back to original just by swapping back the parts.