I lucked into a very low priced 500a Mossberg with a Buba worked on mag tube. It has a 28" vet ribbed barrel with a screw in choke. What should be done after changing mag tube to make it slug and buck shot friendly. The stocks are light so maybe birch. The mag tube should be a 5 round but putting in a new tube I can change to more cap as I assume barrel change will be one of the things to do.