Up close and personal, the difference between 20 & 12 is negligible.
When the ranges start stretching then we see where the differences in velocity, shot count and size start making a difference.
But having seen after action reports, autopsies, and “murder books”, I have no problem choosing a 20ga for home defense. In fact thats what is loaded downstairs.
There’s some light watching for you.
Funny thing, before the great change from scatterguns to AR’s there was a growing number of instructors that were advocating for the 20ga for LE use as well as home defense.
An ounce of lead shot, traveling roughly 1350fps and hitting a 1-4″ area tends to chew up pretty much everything behind it.
Clint Smith said in one of his online class segments, “handguns put holes in people. Rifles put holes through people. Shotguns, right load, right range, will remove a hunk of $&@# and put it on the wall. You’re gonna need some bleach or something after”. I’m not exactly quoting him, but will post a link to the comment.
My wife and kids can all handle the 20, and thats a good enough reason to ignore the 12ga for me.
I really like a shotgun for up close and personal, used a couple of different ones over the years but went to the AR a while back when I was having shoulder problems, the recoil was just too much, even the 20.
But I am considering another scattergun but a 20 this time for me. It will do everything that I need it to do without beating up anyone. A friend has a really nice Ithaca 37 in 20 that I am really tempted to cut down to “riot gun” size.
And the paper figures don’t always pencil out in reality, the “shotgun effect” isn’t just about energy, pellet count and diameter but the multiple entry of the shot simultaneously. It tends to put the nervous system into something of a overload situation.