Wasn't so much worried about lower velocity, I was more worried about the length of the weapon and the fact that it was way too loud for people trying to be quiet like to use even in a defensive role.
(I was on the advance party security sweep. If we ran into 'opfor' it was usually at close range and tehy usually had 'friends' nearby.)
I was thinking of the M-4 in it's specops use with the sound suppressor attached.
But, my unit, as mentioned, wasn't 'authorized' such things.
*sigh*
Was impressed with the M-249 SAW.
The 9mm Winchester 147gr. JHP was originally developed for Spec. Ops. supressed use, and called the OSM, Olin Super Match. It works well in carbines and pistols. As powder chemistry and other technology increases, there is overlap upon previous machines.
The M-4 is that CAR I mentioned. I am sure it is quite effective at closer ranges. However, the military is searching for a larger caliber version, since there are credible reports of failure to stop in close quarters and even general use. It doesn't seem to develop the velocity needed to mirror the larger diameter bullet performance of previous military ctgs. I would think that the highly touted "wounding" effect of the .223 loses some of its appeal when the threat is in your face, and there is not the luxury of burdening the enemy with caring for their wounded comrades, and such. A wounded adversary, even mortally wounded, may still shoot back, which means kill you anyway.
The .30 carbine was favored by Phillipine troops because it was more suited to their physical size. I bet they liked the Thompson too.