Watch your choke tubes and dont use anything tighter than modified. Hevi Shot is usually harder on barrels than steel. Even chokes made for them sometimes lock in place over time. I bought some extended chokes for steel and hevi shot. Puts the whole choke on the outside of the barrel and away from the threads.
870 is stock. Only change I might make (and soon) is replace the shitty ass folding stock with a solid or telescoping. Folding stock is incredibly loose and makes the gun not fun to fire. Can't figure out how to tighten it either.