Would have to see the spec list with what work they are doing . Lapping the lugs by it self isn't going to help much .

Truing the receiver , recuting both the lugs on the bolt and in the receiver to square them to the bolt raceways and squaring the action face with a new chamber that is square and true to the bore is what needs done to see a benefit .

Just lapping the lugs on a stock action and barrel isn't worth the money .