Originally Posted By: Wonko the Sane
Everyone knows that 28gm or 24gm loads from a 12ga hit harder than the same weight from a 20ga, or any other for that matter....

....simple fact innit

For simplicity, I'd look at the 24gm load. Now, the math is easier, it's either a three chunker at 8gm per, or a four hitter at 6gm per shell. There's probably a formula for figuring out how much longer spheres would be in a twenty. Is the 12ga wad a bit heavier?