have a spare 20ga Mossberg 500 that i would like to turn into a HD gun. I would like to simply replace the current 26in Vent Rib barrel with a new one in the 18-22 inch range that has either ghost ring or rifle sights already installed. I have been searching off and on for about 2 months now and havent found a barrel that fits what im looking for. My question is should i just buy a new barrel w/o a vent rib to replace the current one or can the vent rib be removed from the current barrel at the same time that it is being shortened? and how much would be a reasonable price to shorten a barrel and retap it for choke tubes?