Tinker,
I've read before where these 45-70 Ped doubles can be rechambered to 450 nitro cartridges and that they still regulate.
Whether they do or not I don't know.
These rifles are also supposed to have their barrels brazed together which pretty well rules out any chance that they were regulated in the traditional way.
It is also said that they cannot be re-regulated due to the brazed barrels.

If these rifles are originally only jig regulated, and they shoot well with 45-70, and they still shoot well with a 200 grain increase in bullet weight, I think it is amazing.

I wasn't having a go at you in any way.
Sorry if I ruffled your feathers as that was not my intention.