I have a Mossberg 500a made in 92 that has a 28" Accu choke barrel that I am thinking about cutting back to 18.5". Anyone know what the choke or I.D. of the barrel at that point. Right now the end of the barrel is in some penetrating oil. I think the threads are crossed but hoping it just needs cleaned. Who would be good to cut and crown the barrel. It has a vent rib so will need a new sight, would want a rifle sight installed. Could the cut barrel be threaded for the use of Auuc chokes?