Old Joe, I previously posted that I had recently sold a very nice prewar Heavy Duck for $500. It was nicely refinished and well preserved and unmodified. That price to about $700 is about the most a field used HD will sell for. If you damage the muzzle and have Briley whack it and install screw in chokes, it will still be worth at least $500. Don't worry about it and don't spend money modifying the choke. The factory choke is only about .036 or .037, not a problem for a muzzle that thick.