How does a .45 caliber projectile compare to a 12 guage projectile in size? Also how much powder is in a 12 guage 3 inch slug and in a 2 3/4 inch slug? I've shot 12 guages and I'm just trying to somewhat figure out how bad this new ML will kick

A .45 cal loaded with a 240 gr. bullet and 100 grains of powder is not even close to a shoulder pounding 12 guage. They are fun to shoot

A 50-cal is close to a 28-gauge. I think a 72 caliber would be close to a 12-gauge. My 58-cal is close to a 20-gauge.... I think! The next smallest shotgun gauge from a 45-cal would be a .410