US Infantrymen (grunts) carried either a rifle (M-16), or a machine gun (M-60, belt fed), or an M-79 grenade launcher. If the grunt was a radio operator (RTO-Radio Telephone Operator) he also carried a radio ON HIS BACK.
Medics, (whom may or may not have been authorized to carry arms, usually carried an M-16 or a .45 pistol).
Straight leg infantry (grunts) were issued back packs (RUCK sacks) with round edged aluminum frames. Airmobile and Airborne grunts could be issued those packs too. Mechanized Infantrymen were not issued RUCK sacks or bayonets, if they were; they were turned in later in the war.
All straight leg grunts carried an average of about 6 (1 qt) green plastic canteens attached to their rucks and at least 1 metal canteen cup which was used for either heating food or water. Straight leggers also carried 3 to 6 or more hand grenades and a maybe a bayonet. Plus 100 or 200 rounds of machinegun ammo, and two to four bandoliers of M-16 ammo (seven M-16 magazine pockets to the bandolier, each magazine normally loaded with only 18 rounds of 5.56mm; capacity was 20 rounds, but to preserve the magazine’s spring it was compressed with only18 rounds). All of these items were carried in the extreme humidity, thru knee deep mud, and up jungle strewn hill tops.
Straight leg (called light infantry today) infantry carried everything they owned in their rucksacks.
Most straight leg grunts carried maybe 5 to 10 canteens of water (1 qt bottles), 3 to 5 frags (hand grenades), 1 or more smoke grenades, a bandolier of M60 ammo for the machine gunner, 3 or more M16 bandoliers (7 magazine pouches per bandolier-20 round magazines), 2 or 3 C-Ration meals, possibly a claymore mine with its clacker and wire (50 footer), possibly some trip flares for NDPs (night defensive positions), a poncho, a poncho liner, an air mattress, 10-20 empty sandbags…his steel pot (M1 helmet) and an extra pair of socks or two didn’t weigh nothing…cigarettes were in his pockets and helmet band, as was his lighter or matches…of all of that material…it was the water that weighed the most.
In the above described case; the poor M-60 machine gunners and the RTOs had extra weight to carry (Machine gun and Radio).
Average weight carried by infantrymen in Vietnam was (+-) 85 pounds. Numbers below.2 Frag grenades – 2 lb., 2 Smoke grenades – 3 lb., 1 claymore mine – 3.5 lb., Helmet – 5 lb., Boots – 2 lb., Poncho and liner 3 lb., Entrenching tool (shovel) – 5 lb., M-16 ammo – 14 lb., 200 hundred M60 ammo in can – 13 lb., Rifle – 7.5 lb., Machete – 3lb,. Sandbags (empty) – 4 lb., 3-4 days C-rations 6 lb., 1 1/2 gal. Water – 12 lbs.
Adds up to 79 + pounds.
Additionally a fire team shared equipment to include a full sized shovel, a full sized pick (maybe), starlight scope, LAW and radio batteries, for about another 7 lb.
Charlie Company humped that load 7 days a week on a yearlong back packing trip in very rugged country. We did not wear flak jackets because of the heat and heavy load. I believe most if not all Army light infantry units carried the same load in the same conditions of high heat and humidity.
I was there.
There was no average number; you carried everything you could carry. 15 loaded mags were standard. If we were shaky we carried two bandoliers. That was besides the 6 mags in pouches. If you had to make a choice between food and ammo you took ammo. The machine gunner carried two or three belts and everyone else in the squad carried an extra belt. There was a reason they called us “Grunts”.