Browning did not offer one, but you may find an aftermarket Hastings barrel (www.hastingsbarrels.com) that will do the trick.
Will be hard to find, and expensive. Do an internet search for Corson's Barrels.
Try e-gunparts.com or MidWest Gun Works
Almost every gun shop worth its salt should have a slug barrel for the remington model 870,if not then they should be able to order one with no problem.
No
Try gun shops, gun shows, want ad, for sale ad, pawn shop, estate sale, garage sale, Shotgun News, etc..
This should be a Mossberg 500 in a Montgomery Wards suit. Check any dealer for the availability of a slug barrel.
no you cannot. sabot slugs are made for rifled barrels. I would buy a rifled slug barrel.
Your gun is a Standard Weight model made in 1961. The suggested retail price when new was $134.50 with a plain barrel - $154.50 with a vented rib barrel.
Mossberg 1000 barrels will fit the Smith & Wesson 1000 Super 12 only !!
Try MidWay USA, MidWest Gun Works, Brownell's
you can get metal slug games at a flea market