BP may not like the quicker twist.

The twist dictates how long and heavy a bullet you can shoot and be stable. A 10 twist will stablize, a bullet 1.75 long and over 360 gr.

Here is a design I did for one of the East Coast shooters, for his 10 twist barrel. It will stablize in a 13 twist.

My .338 barrel shoots well with it's 14.5 twist and will handle 240 - 260 gr bullets with great accuracy, as noted with the target shown. Though not on a 33/40 but, a 33/357 Max.

For BSing only, a chamber that has a straight taper, with no neck, is best. The cases last longer and won't wrinkle the neck area as much as a case with a neck.