The .223 isn’t legal everywhere for hunting. Here it’s only legal for deer and smaller, and then only with 60+ grain bullets for big game. And from personal experience, I’m still not enamored of the .223 even with heavier bullets.
Much depends on the circumstance of SHTF.
Come SHTF, “hunting laws” will matter little. Even if DNR and game wardens are still in operation (doubtful in most scenarios, but let’s assume they are for sake of argument this once) they will be so overworked that most will chance it. Feed your family, or observe some silly caliber requirement and starve. Most will use the .223 I’d think. Just a guess… Most SHTF scenarios involve some degree of WROL
"ROGUE ELECTRICIAN" Hoping to be around to re-energize the New World.....
Cogito, ergo armatus sum