Correct. The 5.56mm round was designed to wound and disable more than kill, because you wind up with more of the enemy tied up taking care of the wounded. It will kill, and can cause a lot of internal damage even if it doesn't, but a 30 caliber bullet like a .308 or 7.62mm have more mass and pack a bigger punch.
“...The 5.56mm round was designed to wound and disable more than kill,...a 30 caliber bullet like a .308 or 7.62mm have more mass and pack a bigger punch.” [CA Conservative, post 29]
Not the case.
No official US military documentation requesting the development of a new cartridge has ever specified this. It cannot be done, not within the limits of physics, ballistics, physiology, and medicine.
Humans (and indeed any other living organism) vary too much in size, age, location of internal organs, state of health, state of nervous excitation, and other parameters. There is no method to predict what level of energy transfer will injure a living target but not kill it. And not even the finest marksman can be so sure of the position of an adversary’s vital organs that a hit can be assured every time.
According to some authorities, your final phrase is incorrect also, depending on range to target and the bullet in question.
Peter G Kokalis, veteran gunwriter and veteran of ground action in Southeast Asia, wrote (in the early 1990s) that the 55gr bullet of the M16’s original cartridge (5.56mm M193) was more effective at ranges of 100m or less than 7.62 NATO or US 30M2 (WW2 military loading of 30-06): inside that range, the 5.56mm bullet would tumble and fragment inside a human body, expending what energy it did have doing injury to the target. But inside that range the two 30 cal rounds (identical velocities, very similar bullets) would remain stable and punch right through, losing little velocity inside the target (thus doing less injury), and then they’d continue traveling downrange. Beyond 100m, the 5.56mm M193 bullet would have shed relatively more velocity due to air resistance than either 30 cal bullet, and the injury/lethality difference would reverse.