[Smith & Wesson 32 Ten-X cowboy ammo 76GR RN is what Cabela's tech say is proper for it, some coming.]
Have the Cabela's tech test fire it for awhile.
That gun's frame looks to be one that's set up to take/use a leaf-type mainspring ILO a coil spring, and ergo is a blackpowder gun AFAIK.
The early steel is not of a modern mixture, was engineered for BP prior to the introduction of smokeless powder.
The early steels cannot long stand up under the different type pressure of smokeless powder, and IMHO (and others) should never be fired with modern ammo - "Cowboy" loads or not..
Many folks have chimed in with comments that such & such ammo will chamber/fire - and that may all and well be true, but it only takes one shot to burst/crack one open.
It just may not be the first shot.