Thanks for your very kind words, Zoo. It sounds to me, like you'd have fit in well with us, sir.
In all probability, the M15 Smith might well have been as reliable,(as I kept my personal weapons in pristine condition)...but the M15 also used and was limited by issue USAF 130 gr FMJ ammunition at a leisurely 800 fps or so...not much punch there. The .45 and 9mm stuff was well proven and readily available too. And there's always the capacity argument. The M15 did have one advantage, however, and that was as a signaling device with those .38 flare rounds. For search and rescue, they could be fired up through the canopy of trees, pinpointing your location for the helicopter pick up! Far better than tracer which could draw friendly fire.
While I can't speak for the O-2 guys or the OV-10 drivers, those of us in the Birddogs flew with the carbine (CAR15), slung through the door release handle along with two bandoleers of M16 magazines...this was our primary, weapon, in camp and if shot down. FAC's generally did not survive capture, especially down in he lower parts of Vietnam...they were shot out of hand because of the mission and our participation in airstrikes, gunship operations, and artillery fire...they really didn't like us all that much! For the most part we lived in forward operating positions, a Lt. grade pilot or two, an MX sergent and a radio operator, in Special Forces Camps especially, where going armed 24/7 was a matter of course.
In reality, the pistol was only for last ditch use if you had no other recourse if caught w/o rifle and out of position...slit trenches, shower points, 4-holer latrines etc...but as a matter of fact, those are the only places I wasn't carrying a CAR15 or an AK. FAC units did not disarm pilots when we flew into major bases for maintenance on our birds. We shacked up for the days required at friendly fighter squadron barracks or with a desk bound buddy and kept our weapons with us.
Nowadays, as an old man and in a civilian farm town environment where laying down a base of fire and participating in flanking maneuvers are less likely, a good revolver is plenty reliable. I'm not retired LE nor ever have been, so my reaction to attack or potential attack is to retreat where possible, and my duty is only to my immediate family...those that depend on my continued support are all that count in my world. Given that, I find a revolver often is more than enough...I find my wife's 637 Smith or my own M60 ample for our daily lives.
I've wandered from your thread, and do apologize; the M15 is a truly a fine piece, well made, and only over shadowed by the greater capabilities of the Magnum 66 and 19. Best Regards, Rod