I've got a Ruger Mark-II All-Weather in 7mm Mag. The trigger pull is very stiff, around 6 pounds. What will a good gunsmith usually do to lighten up the triggers on these guns? I would like to have it set at 3.5 pounds. Could I try different return springs to try to adjust the trigger pull? I removed the trigger mechanism from the gun and it looks like the contact points have already been polished, should I try to polish them some more. What do you use to polish the metal with? Thanks.