If you decide to lighten the trigger pull yourself, I have a few suggestions.
Remove the side plate and remove the mainspring, hammer, trigger return slide, and the trigger. Remove all the oil/lubricant from the parts and the inside of the frame. Coat the inside of the frame and the parts with blue layout dye. Reassemble the gun and dry fire about twenty-five times.
Disassemble the gun again, remove the parts and look for any areas that have had the layout dye rubbed off. A small area of rubbing may indicate a burr (such as just behind the trigger pivot where the cylinder stop plug is upset into the frame).
If there is a large area rubbed, under the trigger or the hammer, it can mean that they are not perpendicular to the pivots (crooked that is; a frequent condition in modern S&W's) and will need trigger or hammer shims to keep them from rubbing the frame.
Note that these conditions can increase the required trigger return spring pressure, which is a factor in the felt trigger pull weight. Also, note that lightening the trigger return spring does not affect the primer strike at all; it only affects trigger reset.
Polish the inside of the trigger return slide when you have the spring out.
I have found that if a 12 lb. trigger spring does not reset reliably, there is some drag somewhere that is causing it. I suggest buying at least two return springs (12, 13 lb.), and working with the gun until it resets reliably with the 12 lb. spring. The return spring affects the feel of the double action pull as much as the main spring.
If you change the main spring, polish the mainspring strut as long as you have the spring off.
By the way, rubbing alcohol will remove the layout dye.
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