Re: M2 carbines
My "legacy" non issue sidearm in Viet Nam ('69-70'), that was handed down from the individual that I replaced, was an M2 that had been converted years before into a pistol configuration. What with back to back taped together 30 round magazines, it was a most effective little close quarter weapon. It was also in point of fact very controllable in FA usage. It almost felt like a FA 9mm H&K MP5 in use. In a very close order drill, the M2 was also fairly widely known to be a weapon that you did not want to get in front of. It would deliver the rounds, it was reliable, and it was relatively accurate (considering).
My M2 also served as a most effective visually deterrent 'loaner' for all of the various officers assigned to be the monthly pay officer for the unit. The pay officers typically had to ride 20 miles or so through oftentimes rather questionable loyalty, high road traffic territory to pick up in excess of $50,000 or so in cash to pay all of the other troops in the unit. The usual 1911 officer's sidearm (which was often holstered) just did not have the same threat to life and limb factor as the pistol gripped exposed M2. The local bad guys where I was did not take to long to figure out that an officer coming out the disbursing cashier with a large brown paper grocery bag on pay day was a reasonably good target. At the time, the old 'distract the officer and driver and then reach into the jeep to grab the cash' gambit occasionally worked effectively as a tactic against the poor assigned monthly pay officer's of other units. Those particular hit and run payroll thefts tended to generate great smoke, super nasty paperwork, and occasional non judicial punishment for the officers involved. However, it seemed that having the pistol gripped M2 in your lap with your hand on the grip, barrel pointing out into the passing traffic, and finger around (no not on) the trigger was something that they did not want become involved with. We went through 12 pay cycles without a loss while I was there. Great little gun.