I seen the other day on http://www.content.overture.com/d/home/
I seen where there was a web site that doe's special reloads/manufactor of antique and obsolet ammo. I didn't open it up because all the firearms I have you can still buy off the self.
In the search area you might type in the words Antique and Obsolet Ammo
. If you don't get any hits then play with the words untill you do. You might even try Ammunition Maker/s
. If you need help please contact me.
Best of luck to you and be safe. Just remember if you cant get the exact ammo for it and you try other types of ammo the gun can blow up on you. If you cant shoot it, who cares because when Sears sells something and is still around can be worth many $'s.