I guess this may be a true/false question, not sure.
I was questioning a reloader about his 45/70 loads using Cast Performance 470gn. He is using 47 to 48 grns of RL-7. My thinking was this would easily put him in the 70,000 to 80,000 psi range. His response was that using either Cast Performance or Performance Cast (different companies, same bullet) there is less bearing friction with lead cast so loads can be increased with while still keeping pressure manageable.
I can Partially see how this might be similar to having graphite lube on a bullet but with hard cast would it be the same?