For years the USAF's Strategic Air Command used the M2 Carbine as its first line shoulder arm (until late 65 or early 66 I think) for the security forces. If necessary backup units could respond with heavier firepower (BAR's). The other units (non SAC) used the M1 Carbine. General Curtis LeMay was one of the forces taht got the M-16 a try out with the government. We in the marksmanship unit used to LOVE to take the M2 and put it in a M1A1 stock (folding paratrooper) and go jackrabbit hunting on the ranges with it (full auto 30 RD Mags) fired from a jeep with the windsheield folded flat
! We used to make sure that the mags were good ones and usually they worked fine, the magazine is one of the main problems with the carbine, and jamming. Sometimes we had the linseed oil in the handguard smoking from the heat
. The carbine was very controlable on full auto in that configuration and even more so in the full stocked model. At the 50 yard line from the hip on full auto, at a shilouette target on a good day the hit ratio was over 85%-90%. Thats nothing to sneeze at. Muzzle rise was very controlable. The few drawbacks were lack of power, and a rainbow trajectory, and damaged magazine lips. The carbine was much more prone to this problem than the M-14 or the M-16.
In Spain, and some other countries, the local government restricted the USAF to shotguns for guard duty. When this happened the old M-97 Riot guns were used. The reasoning behind this was that 00 would not carry as far, or penetrate as much, as a rifle round. The one time one had to be used was in Spain IIRC. The guard fired at an intruder and a single pellet of 00 "found" the side of a B-52 right at the RN console! It would not have brought that BUFF down if it had happened in flight, but it did something like $70,000 worth of damage........in mid 60's bucks, plus left the bird with no RN system. They had to fly it in formation with another one all the way back to Evrette, at the Boeing plant to get it fixed. I often wonder what would have happened if the guard was using a carbine, or better still still an M1 Garand? The carbine is a good weapon to learn to shoot with and to learn to hit with. As i said before, If that is all one has at hand when trouble arises it is better than rocks. A whole lot better. If one knew that trouble was coming for certain then there are better choices I think.