Well this is how I went about it, probably easier ways but this is my method:
-Started by spreading some valve lapping compound on the bolt, action bars, and action bar guides(lack of correct term?) inside the action. This helped lap the surfaces and show where the majority of the metal to metal contact was occurring.I watched a couple t.v. shows and cycled the action while doing so.
-I then filed down the top/bottom edges and any burrs on the action bars using a small hand file, these areas then got sanded with 400grit, 600grit, and 800grit, followed by a final polish with a dremel and polishing compound.
-The bolt got the same treatment along the outside edge(area you can see when action is closed) 400 grit, 600grit, 800grit, and dremel polish. Also on the bolt the grooved area that the ejector slides along needed MAJOR work, started with the small hand file, 400grit, 600grit, 800grit, dremel polish.
-The path ways that the action bar guides within the action itself only got polished with the dremel as it was not really feasible to try and sand these areas, although more time spent here would probably pay off.
-All areas were then cold blued for abit of protection and then lightly polished with super fine steel wool and oil.
I'm sure I'm likely forgetting something but these areas were the main culprit. Its no model 12 or older wingmaster but it'll do and it was a fun job. The main culprit was the trueness of the action bars, the don't seem to be perfectly lined up but this cannot be adjusted as it is the way they are manufactured, they're straight just not aligned very well.
Haven't fired anything in this shotgun yet so I'm sure that will help.