Thanks for the help! I ordered .38 LC cowboy loads from Cabellas and should have them soon.
There is no indication that this gun is made for smokeless powder nor would I expect that from a gun made in 1887. The screw that anchors the cylinder pin comes up from the front at a 45 degree angle upwards, definitely not transverse.
I never heard of the "hot needle test" but a hot needle did scratch the grips without any pressure so there is some polymer material in them. They are very worn so wondering if they could be old vs just fakes designed to look old. Does anyone know if there were "artificial ivory" grips back then? Could they be from the factory?
I paid $1500 for the gun at a local gun show so I certainly didn't pay for ivory grips, just a fun shooter and attractive showpiece!