In terms of energy/torque, the 12 ga is the most powerful. That's the first pic above, 00 buck. But the are heavy, well because Einstein was correct E=MC2

I have tested a 7.62 x 54 on a bolt, and it fired as well, but again the weight limits distance...I like using the 9mm because they are light and have proven to be a good balance of power.

The light carbon fiber bolts, and the fact that the bullet is not enclosed in a tube, like in the barrel of a gun, it cannot realize its full power...It expands the casing and pushes back on the bolt...Although it still fires the projectile with a measure of force!