THE most accurate load I ever built for my .45-120 was configured around Curtis and Harvey CANNON GRADE powder, with little or no compression.
A BULKY F grade would be my second choice.The old original Elephant powder out of Pernambuco, Brazil was THE powder for the longer 45s.
Dunno where this 80 gr max nonsense is coming from,...
and would suggest that the BPCR forum RIGHT HERE is no slouch when it comes to a few years in the game and a bit of savvy.
Even a full-power load is far more difficult to achieve in such a long cartridge than a .45-70 or .45-90.
Sorry,....that's just horse chit.
GTC