Due to all the 'modern' data for the .45/70, that round has become what is probably the easiest round there is to pick a pressure range and load to that pressure.

It matters not if you want to load to anything between 18,000psi all the way to 55,000 psi - any level in between has data listed to pressure with a variety of bullet weights and syles.

At 40,000 to 45,000 as suggested max for double shogun actions by Ellis, you can actually load to over 2,400fps with 300's, 2,200fps with 350gr. bullets and 2,100fps with 400's - or anything less the data is available.

Even an original Trapdoor Springfield (in good shape, of course) and loaded to sub-max loads (max listed is 28,000psi) using Varget, 3031 and Benchmark, can load to over 1,800fps with a 385gr. cast bullet & 1,800fps with 400's. Pressure-wise, they are soft loads, yet smack big game, big time. Drive a 300gr. Nosler Partition at 2,200fps for 300yard deer blasting? Safe max. listed for the trapdoor, with 4 other loads over 2,100fps. That's 300fps over factory ammo. Not bad for a round developed in 1873. That 300gr. jacketed bullet at over 2,200fps matches the .405 Winchester ballistics today.