You will stretch a Contender frame with too-heavy .45-70 loads. I don't know about the G2 but don't hotrod it either. Besides pressure, the recoil will hammer all the internal parts, so don't.
The big question is, what is Trapdoor pressure?
Data Source.. (CUP)
Lyman…….……18,000
Speer…….…….21,000
Hornady..…….25,000
Hodgdon………28,000
Factory……..…18,000 (reported)
.