I'm glad it cycles for you. I had one that constantly failed to extract. I liked the cartridge since I had open tops that I shot 44R. Ended up selling it and bought one in 52-50,

https://castboolits.gunloads.com/showthread.php?162479-My-foray-into-38spl-black-powder-loads

 I have loaded and shot 357 magnum cases in my 1892 Japchester.  It is most definitely accurate but it is not at magnum power levels.  I never chronographed it.
I used unsized Starline brass. Brass that had been fired with full power loads of H110. This helped reduce fouling in the chamber, "blow by", to nothing. I don't have the exact load info near but....
158gr Accurate mold at .360 in 30-1 alloy, DGL black powder lube, Swiss 2F ( don't have any 3F) and CCI small pistol primers.

Well, I really don't like the way the 1860 grips were cut down to make them thinner.  I located one ASM 1860 walnut grip on ebay.  Haven't found another, but did come across a complete ASM 1851 grip, so I have it on the other one for now (until I find another ASM or even a Uberti 1860 grip (which is close enough). 

Hope to finally use them at the local match in a couple weeks. SWEET!

Johnny is right on all accounts. It can change your opinion of black.

I look forward to seeing how it works for you.

I had a Hubley Luger.   I am guessing the Dime Store in town had little turn over as i got it when I was seven in 1973.   It was a prop when my sister was in the sound of music.  It came back in pieces.   Grrrrr.