WELCOME ABOARD!
Sounds like Firehole Arms made their ammo straight off the Q/Faxon recommended load list, which I found to be waay too hot. They might also be in the market for a Sheridan gauge! I don't think I'd shoot any more of it, maybe salvage the cases after running them through a proper die.
I wouldn't recommend for anyone else, but I found that around 32gr of TAC or CFE 223 in a 16 inch gun for 185gr CX or GMX supers seems to work pretty well. If you try ANY of this, MAKE SURE YOU START LOWER AND SAFER!
For subs, I used CFE Blk at around 17gr for SMK 300gr at 1088 fps. BEEEEE CAREFUL!