Wow! It seems that some of your .45 BPM loads even surpass the .357 Mag (Factory loads vary from one mfg. to the other)
With Swiss FFFg and a roundball, the Walker easily beats a .357 factory load in both velocity and stopping power department.
One question though: Would your BPM loads wreck havoc on the barrel wedge of the Walker? With such pressure coming to bear on that open top frame, I'd imagine the wedge and the arbor pin is taking one heck of a beating.