Just for kicks and giggles, I did a little experimenting with .330″ round balls in 8MM. The balls were lubed with Black Magic and loaded ‘as cast’ to the ball equator.
I charged the case with 2 grains of Bullseye and located it with a one inch square of 3/8″ loft Dacron.
I filled a box with old newspapers and stood the box up so the ball would go through the layers of paper. I fired the test round with an old sported 1941 Kale Mauser.
The ball penetrated a little over 2 inches of paper. Below, you can see the equator band from engaging the riflings.
In the next photo, you can see the spiral shaped deformations in the forward side of the ball from spinning into the paper.
I’d have to run this load across a chrony to get the velocity, but I would imagine a .330″ round ball with enough energy to penetrate two inches of newspaper would certainly kill a squirrel at reasonable distances.
The muzzle report was about like a standard 22 short.