Allow me to make it complicated. Most 20Ga Coach Guns are fairly light. Over the years, 20Ga shooters asked the ammunition manufacturers to provide ammunition to make a 20 comparable to a 12. The ammo makers complied. The result is some really potent
20Ga ammo. "Target" ammo for Shotguns is different than "target" ammo for pistols. Shotgun "target" ammo is loaded to break clay
birds at 30 yards and beyond. The result of all this is recoil. Lots of recoil. There are only a couple of ammunition makers who offer
light recoiling 20Ga ammo. For all the above reasons, most CAS shooters prefer a 12Ga, heavier gun, lighter loads available. The
12Ga becomes the Go-To gun for most.
This all becomes mute if one reloads. If you don't reload, until you find the light recoiling stuff, your gonna get hurt.
Coffinmaker