ORIGINAL: CZ2506
There must be something about the case designs that causes such significant differences in burn rate to have this much effect on pressure. Muzzle Energy should be close to the same given equal bullet weight and close to equal MV. So is the difference in recoil related to time of acceleration?
That is my opinion as well. The fact that the powder type here is constant is a big help. Lots of factory loads use different powders for different calibers. The way the powder burns has a lot to do with what kinda whallop you are going to get out of a gun.
I'll tell you right now that a faster burning powder is going to punish you more. Anybody reload shotgun shells? I remember being a youngin' and shooting some fast buring 20ga buckshot my father loaded out of my light double bird gun and wishing I'd never taken up hunting. He went back and used something a bit slower and I could shoot all day and not bat an eye. Velocities were nearly the same, payloads identical... there is something to burn rates and case designs.