Rich;
That is correct. If you reduce the wall thickness by .010" then you will of course be enlarging the bores by .020". This was based on 22" of the barrels being enlarged which would basically be from the cones forward. Since you were speaking of this for a Woodcock gun I assumed you would not want the chokes increased by .020" so would enlarge them as well. As Lefevers normally have long chokes if you leave them totally intact your gain would be a bit less, but probably still on the order of 4 oz (lb).

Miller/TN
I Didn't Say Everything I Said, Yogi Berra