I don't know a whole lot about the Mossberg shotguns, or any other guns for that matter, but I do have a 500A. I don't think that the barrels are interchangeable because, if I'm not mistaken, the 835 is a magnum gun. The 500 isn't magnum. Check out cabela's, bass pro shops, gander mountain, or any other outdoor store because I think they do sell different barrels for the different shotguns. Maybe check out the Mossberg website for a different barrel.
Nope, the 535 and 500 maybe, but the 835 is backbored to almost 10 gauge dimensions, which is why they throw such awesome patterns for hunting. If you want a HD barrel for it buy one of the turkey barrels and put a improved choke tube in it.
I assume you're looking for a shorter barrel for your 835 not a 500 since there are plenty of after market HD barrels for 500s.