The only definite in the aftermath of a rifle blow up, is that you have a blown up rifle. I read a bit of the bantering on the other thread. Some made sense, some repeates of rumour, some mere defensive. We have no idea what the load was. Overload ???, bore obstruction ???, underload ???
Wether a published load or not, I will say I feel 40-ish grains of RL7 is too much for a 140yr old metalurgy. Pulling down the rest of the ammo is part of the investigation. The quick easy answer is to not use nitro in a Trapdoor, thou that is a bit in-complete.

The only rifle blow up I actually examined was traced to salvaged powder that was believed later to be 4227 and not 4350. In a 165gr 30-06 load it bulged the barrel of a featherweight M70, splitting the stock. Owner fired a second round "To be sure" ... he was sure after that, as the bulge let go and split receiver as well.