The 12 gauge double barrel Remington is S-Mart's top of the line. You'll find it in the sporting goods department. They're made in Grand Rapids, Michigan, and retail for about $109.95 - Walnut stock, cobalt blue steel, and a hair trigger. Shop smart - Shop S-mart. Nehehehe...
It doesn't look like there are much out there.
I have a 16 gauge double barrel for sale.
Where can I buy a forend grip for a wm Parkhurst double barrel 12 gauge
Try e-gunparts.com
the most u will get is $5. ill buy it from you for $10
Find an authorized Remington Repair center. You can find a list on Remington's web site.
I found a new unfinished one at: http://www.gun-parts.com/index.html/
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.
Cabella's
Go to Dunhams... They have everything.
Caliber is .243, buy ammo in .243.
You would have to list the model number of your shotgun,to identify the maker of your sears and roebuck shotgun,in order to get the correct buttstock.