"Energy” ratings are simply theoretical equations that have absolutely no bearing on a rounds terminal capability. They in no way factor bullet design, or terminal performance on soft tissue, which is the most critical factor in the job bullets are called upon to do. Anyone who has ever hunted animals to any extent knows this factor well.
Imagine you went bowling, and took a bowling ball and a hand grenade.
You hurled the bowling ball at the pins. It smacked them, and sent them flying.
Strike.
Now, imagine you took a hand grenade, pulled the pin, and slowly lobbed it underhand into the pin deck. While it might weigh less than the bowling ball, and be traveling slower, it completely blows the pins into bits. Its ability to terminate the pins is greater since it utilizes a more efficient terminal function (“exploding” rather than “impacting”).
Same goes for the .223 vs. .308 debate.
The .308 arrives on target, and delivers a heavy bullet at a moderately high speed. It punches a hole, and displaces tissue. It’s terminal capability is reliant on it’s ability to strike critical organs upon impact.
The .223 arrives on target a lot faster, and by virtue of it’s lightweight design, undertakes an entirely different ballistic operation when it impacts the target.
Instead of “punching a hole” like the 7.62, the .223 tumbles, or fragments. This tumbling causes a more destructive displacement of tissue, which translates to a higher degree of terminal capability. The fragmenting causes secondary missiles, which not only increase the chances of impacting a critical organ, but also delivers a higher degree of hydrostatic shock. Read the stories from Vietnam about soldiers shooting gooks and completely blowing their limbs clean off with a single .223 round… My favorite quote…
“I shot him with the black rifle, and it opened up his chest and spilled his guts so lightning quick you would have thought he had swallowed a lit stick of dynamite…”
Ya ain’t gunna get that with a .308.
Also, you have to consider the practical operating characteristics of each round are different as well. You can carry more .223 ammo afield than you can 7.62. The .223 recoils less, thus recovers faster to engage other targets. A milder recoiling round is also MUCH easier to shoot under stress. I am by no means a recoil sensitive individual, but in a stressful situation shooting at targets a long ways away, less recoil is always better.
Of course, the .223 has a lesser practical range than the .308. And the .223 sucks ass at punching through improvised cover. The .308 is better in those arenas.
But the .223 still has it’s place for certain operations, just like the M1 Carbine had a place for roles the Garand couldn’t fill. They both do different things.
They were both “guns”, but they had different roles. But to say the .308 is better because it’s bigger is like saying a bowling ball is better than a hand grenade.
Terminal ballistic function can’t be measured by a simple mathematical formula like “energy ratings”, but they are the most important dynamic of round selection.
I really don’t give a dog’s ass, as I own both .308’s and .223’s. They both have a purpose. I don’t try and call on my PSS to fill the role of an AR no more than I would call on a M1 Carbine to fill the role of a Garand.