Today I did some test work for another shop on a S&W 645 that was in for a detail clean and strip and for a function test.  The owner complained of inconsistent primer strikes causing the gun to malfunction.  Upon further inspection it was determined that the mainspring had been trimmed to lighten the trigger.  This is one of the most common mistakes the home enthusiast makes.  When you start cutting coils from springs you run the risk of losing the reliability of the gun.  This is especially prevalent in S&W J frame models. 

If you want a trigger job done on your favorite gun, you should have it done by a competent gunsmith.  There is more to a trigger job than semi-chrome polish and cutting mainsprings.  You always have to change relationships of other parts.  Unless someone has walked you through this process before, you will run the risk of butchering your gun.  Be careful and leave the gunsmithing to people with the know how. 

By the way, if you have a dremel tool at home you should also have a license to run that tool.  Otherwise you may end up with a great gun that is ruined.  Be warned.