Actually I seat the bullet to the length of 1.255" which puts it right about at the top of the band marked as .422" in the right sketch. This is the bullet from the custom mold I make the bullets from. So, That shouldn't be a factor in that it's smaller than barrel diameter.

I noticed in checking right at the mouth of the case with a loaded rounds I brought home, the diameter ranged from .472-.475". I don't know why the variance since they all go through the same taper crimp die. I'm going to "tighten up" to about .468".

Accurate Molds: Custom Bullet Molds