IMR4350, I have an early 870 Express too and have had no rust problems but the later ones seem to rust by just looking at them. If I bought a later Express I'd strip all the oil off of it and treat it with Eezox.
The only thing I don't like about a Mossberg is dealing with the shell stops when you take them down.
If I was looking for a Turkey gun I'd find an Ithaca 37 30" full choke and go hunting. Where I turkey hunt is in woods and not fields so 40 yards is a longish shot.
