Some Redneck Science: https://www.alloutdoor.com/2018/10/09/drywall-penetration-9mm-vs-223-vs-22-lr/?utm_source=Newsletter&utm_medium=Email&utm_content=2018-10-16&utm_campaign=Weekly+Newsletter
I would of liked to seen him run a 5.56 either green tip or a 77grn.
For the average prepper, any shoulder fired weapon, regardless of caliber, will be better at a first round hit than a handgun especially as range increases.
Rather than fussing about numbers, you should be concentrating on capability. Beware of the Expert Rifleman. He can pick up any rifle, after a few minutes of familiarization with the trigger (they are all different) and the action, can hit anything he can see and within the limitation of the round, consistently.
Not some one-off.
Someone mentioned the 5.56 out to the 600yrd line.
Go to a NRA High Power Rifle competition and see what the guys running AR15 are shooting. They are shooting NM 20inch barrels. Anyone who is serious about competing are not shooting a 16.5inch barrel. They are also shooting at the 600 line 80grn VLD bullets, sitting atop a compressed charge and exceeds the magazine. They have to load the round through the ejection port, turning that semi-auto rifle into a single shot. Even Nosler reloading manual mentions this.