I spent two tours in Vietnam...the first in 1970, as an airborne Forward Air Controller flying an O-1E serving with 5th Spl Forces guys at An Loc, lll Corps, B-33, north of Saigon. My Air Force issue handgun was a M15 Smith, that I returned to the squadron armory soon after checking out in the Birddog. The camp I was assigned to had many unusual firearms...Swedish "K"s, M1 Carbines as well as some heavier stuff. They gave me a 1911a1, and a "tanker" cross-chest rig to tote it, but I soon got my predecessor's Browning Hi Power, 9mm. I kept this till I DEROS'd in late 1970. 9mm ammunition was easy to come by while I was there.
I saw no Pythons while there, nor during my 2nd tour. Revolvers, in general, were not carried by anyone I served with in the bush, as they lacked capacity in actual combat. That's the reason I left mine down in Bien Hoa at the squadron. But personal weapons, from the states weren't difficult to get into country...but getting them home after your tour was over was nearly impossible. The REMF MP's searched luggage for contraband extensively: guns, ammo, grenades, drugs etc. The Hi Power I carried was given to my successor...wish I'd gotten it home with me.
In camp, while flying and pretty much 24/7, I and the rest of the camp carried M-16's...mine was the Air Force issued CAR-15...very similar to the M-4 now issued. Mine was accurate, and I was supplied with Air Force ammunition though our normal supply chain. The Green Berets from our B camp, when going up to one of the A camps routinely raided my CONEX for our ammunition...and this was a cpl of years after the Army sorted out the M-16 jamming problems.
The picture below is from Feb 1970, while I still had the M-15 S&W. That's the O-1E (Army called them L-19's), and I'm loading 2.75" Willie Petes. White Phosphorus was our marking rocket for airstrikes/gunship work...I also carried HE and/or flechettes from time to time. The carbine was slung from the right door ejection handle with a bandolier of magazines hung from the butt. We strung grenades, usually smoke, but occasionally frag from 0.040" stainless safety wire strung across the back of the cockpit seat. Note the stencil on the door, just below the open cockpit window..my special forces nickname...also the flare pods outboard of the rocket tubes...very useful for dropping ammo, medic supplies and sometimes a case of beer to teams in the bush. I'd cruise along at 80 knots just over the bamboo thickets and drop it on their call.
Best regards, and sorry for the digression.... Rod