NASA knows that a 5 gr projectile, at
15,000 fps, will blow a 1.5" hole in 1.5" thick, hard anodized aluminum tank armor. It was an aspirin sized wafer, made of plastic, fired out of a "rail gun".
A lot of VERY experienced combat vets all said .30 Carbine ball ammo sufficed, out to 75m, anyway. At that range, the .30 c's blunt bullet is down to 1700 fps and 700 ft lbs, and it over penetrates men's torso's, too. So it delivers at most 600 ft lbs.
Cirillo, NYPD stakeout specialist, saw a few men get shot with a special 100 gr, 2000 fps .30 Carbine load, and was quite impressed with it, but remember, hit or miss, stop or not stop, is the same 50-50 outcome as a coin toss's heads or tails. 3-4 straight "heads" or tails, in as many tosses, is a commonplace thing, and 5-6 straight are not unheard of, by any means. So unless you've actually seen about a dozen CHEST hits, on as many men, with your own eyes, you don't know a thing beyond what can easily be just luck, misperception, or outright lies.
For instance, LaGuarde lied in his book GUNSHOT INJURIES, about what really happened when he and Thompson tested 7 different handgun loads on steers, in 1907. The .45 auto was not tested by them at ALL. The .45 L Colt was (I think) the .455 Webley, 476 Eley. The first day, they shot 1 steer with each of 6 loads, in the guts, 1 minute per shot. ALL were still standing after 6 minutes, and were killed with a sledgehammer.
They abandoned THAT bs approach, and next day, "rapidfired" the guns into the chests of another 7 steers. one was a retest, I forget why. The FASTEST drop was with .38 L Colt, and on autopsy, was proven to be the result of a severed aorta, and still took 40 seconds.
A man can easily be shooting, clubbing or stabbing you 4x per second, with EACH hand, so only an IDIOT considers even a 1 second interval (between shot and stop) to be an acceptable standard. Blood loss ALWAYS takes at least 5 seconds to shut down a man. This is easily proven, with a choke hold. So blood loss, or loss of organ function (other than the brain, or the spine above the attacment point for the nerves to the arms) is a lost cause as a hope for stopping a man.
Only shock has the potential for the INSTANTANEOUS stop that is needed for realistic effectiveness. Sure, shock can fail, but it's your only realistic hope. 223 sp's are easily PROVEN, with chest hits, to put big dogs down, and they can't get up again, 48 or more times out of 50 shootings. 230 gr .45 jhp's do NOTHING of the kind (much less ball ammo) A million people in the US are dog bitten each year, and as many more escape such a fate, by pure luck. So a defensive handgun's performance against dogs IS relevant. The .45 has the SAME momentum and 4x the "frontal area" (of the bullet) as does the .223, so obviously, the far greater energy (actually transferred by the .223 sp) is doing SOMETHING desirable. We CAN match (as proven on animals) the performance of the 223 rifle (especially if the rifle is used at 50-100m, where we KNOW it's still very effective against dogs)