"With a 110 grain bullet, velocity on the .30 carbine is 1950 fps. With the .300 blackout, the velocity is 2350 fps."
"That means the energy level of the .300 blackout is 45% greater than the energy of the carbine."
True, but the little M1 Carbine is a lot lighter and with a folding stock it's just the right size for riding around behind your seat. You can't get an AR to fold up like that.
The M1 has another benefit as a go-to-war machine that were not allowed to talk about here but with about 5 minutes on your bench the M1 Carbine moves into a category all its own.
I think the M1 Carbine is a underrated. But you can get AR platforms at about the same weight.
The AR rifles are more powerful, and they are much, much cheaper and easier to get ammunition for (at least in 5.56). You can make a good case that the M-16 has most of what LTC John George suggested when he asked for a fighting rifle improved over the Carbine and the Garand in “Shots Fired in Anger”.
The M1 Carbine is cool little rifle. Just not quite as versatile and powerful as the AR-15 and various clones.