I’ve wondered how the heavier (longer) projectiles would perform from that twist. The reason I bought the shorter 250 REAL.Rod, You might try shooting .50 Maxi Balls in the Great Plains. They surely will penetrate just fine, even at handgun velocity and recoil with a 50 grain load of fffg isn’t objectionable at all.
A Plains Pistol is honestly a bit low on my list though, but I do feel I need one. But then I have irons in many different fires and BP has barley been smoldering these past few years as the one outdoor range is a bit over an hour one way since I moved.