I missed this the first time around. Just to put a 4 gauge shell in perspective...
Left to right - .410 bore, 28ga, 24ga, 20ga (old red hull), 12ga, 10ga brass case, 10ga 3-1/2", 8ga and 4ga. I didn't want to unwrap the 32ga box, so it's not shown. 4ga... that'll rock the boat!
Iv'e posted these before, but to show how big a blackpowder 4 bore bullet can be, observe these three rounds. left to right. .58 caliber, .72 caliber conical, 4 bore. Yea, it's a monster....