The problem is not the 9mm.
The problem is that they are using ball ammo—The worst choice out of all the available 9mm cartridge designs!
The top 9mm loads (e.g. Speer Gold Dot 124gr +p+, Winchester Ranger 127gr +p+) are just as effective as the top loads in .45ACP, .357SIG, and .40S&W.
But these are all modern JHP designs. Out military is not allowed to use them.
Good answer Joseph..you are spot on.