The XM16E1 assault rifles are used by the soldiers of the 1st Battalion, 7th Cavalry Regiment, including Lieutenant Colonel Hal Moore (Mel Gibson), First Lieutenant Charlie Hastings (Robert Bagnell), Second Lieutenant Jack Geoghegan (Chris Klein), Sergeant Ernie Savage (Ryan Hurst) and most U.S. Army soldiers. Later on the film during the Battle of Landing Zone X-Ray, Joe Galloway (Barry Pepper) uses one as well. The rifles used in this movie were not actual XM16E1s. Real historical XM16E1s had only a partial magazine fence. The rifles were actually M16A1s mocked up to look like XM16E1s, modified with chromed bolt carriers and 3 prong flash hiders.
M1 Carbine
A Korean War-era M1 Carbine is carried by the ARVN interpreter dressed in tiger stripe fatigues. He appears in the scene in which the NVA scout is captured and interrogated. Viet Minh soldiers also use them against the French during the intro.
M60 Machine Gun
The M60 machine gun is used by several US soldiers. Various door gunners use them as well. Specialist 4 Russell Adams and his assistant gunner Specialist 4 Bill Beck also use an M60 in a deleted scene.
M1911
A Colt M1911 is used by Command Sergeant Major Basil Plumley (Sam Elliott) as his main weapon since he prefers the .45 over the XM16E1 (which he calls a "Piece of Plastic"). It is strange to see the first model of the M1911 being used by Plumley, since the M1911 was replaced in 1924 by the improved M1911A1 which was the sidearm of the US Military in the Vietnam War, World War II and the Korean War. It could be that the M1911 was used to make Plumley more "Badass". As if a Sergeant Major that fought against a entire regiment of heavily armed NVA and a NFL Battalion armed only with an M1911A1 was not badass enough.
M1911A1
A Colt M1911A1 is seen in the holster of Lt. Col. Hal Moore and most of the soldiers of the 1st Cavalry Division that appear in the movie. Some soldiers use the M1911A1s.
M26 Hand Grenades
In several scenes, U.S. soldiers can be seen with M26 hand grenades strapped to their pouches.
PPSh-41
The NVA and the Vietcong use PPSh-41s submachine guns during the intro sequence and the rest of the movie, with both the standard drum magazine and 35-round box magazines.
PPS-43
The Viet Minh uses PPS-43 submachine guns along side their SKS's and PPSh-41s to kill the French soldiers in the intro sequence that takes place in 1953 in the Indochina War. During the rest of the movie, the PAVN (People's Army of Viet Nam, the formal name of the PAVN. Also known as the North Vietnamese Army or NVA.) and Vietcong (Informal name for the National Liberation Front, or NLF.) use the PPS-43 sub machine guns against US Army soldiers in the Battle of Ia Drang.
AK-47
During the movie the North Vietnamese Army (NVA) use genuine AK-47s with milled receivers. Victor Charlie (The official name NATO gave to the Vietcong) fighters also use AK-47s. The AK-47s used in the movie were built by the Movie's Armorer Mike Papac.
M79 Grenade Launcher
Various US soldiers can be seen carrying M79 grenade launchers in a few scenes. Specialist Galen Bungum (Blake Heron) uses one since he is the grenadier of Sergeant Savage's squad.
MAS-36 Rifle
In the opening scene where the French soldiers are ambushed during the French-Indochinese War, various French soldiers use MAS-36 rifles.
Smith & Wesson Model 13 Aircrewman
The .38 caliber revolver pulled out by Maj. Bruce "Snake Shit" Crandall (Greg Kinnear) is most likely a Smith & Wesson M-13 Aircrewman, an unsuccessful lightweight aluminum-cylindered revolver designed for US military flyers. This was part of a generally badly thought-out push to make things from aluminum in the 1960s, also resulting in the M551 Sheridan's lightweight aluminum armor that could be penetrated by machine gun fire and a number of disastrous fires on warships with aluminum superstructures. In 2007, the real Crandall was awarded the Medal of Honor for his actions at the Battle of Ia Drang Valley.
GE M134 Minigun
A pair of GE M134 Miniguns are seen mounted on the gunship Hueys that rip apart PAVN soldiers in the climax of the film, and one is also on display on a table near the beginning of the film.
M1928A1 Thompson
As the American soldiers are heading off for battle you can see a South Vietnamese soldier holding up an M1928A1 Thompson with a 30-round magazine.
Browning M1919A4
Two Browning M1919A4s can be seen mounted on French jeeps on the intro sequence.
MAT-49
Various French Soldiers use MAT-49 submachine guns during the opening Scene. Various NVA and VC soldiers use them during the rest of the movie, probably scavenged from French and South Vietnamese troops during the Indochina war.
RPG-2
An NVA soldier wearing a gas mask uses an RPG-2 (Vietnamese made version was known as the B-40) to kill American soldiers.
Actually it is not a gas mask - it's a protective hood and goggles worn to protect the shooter from the blast when firing the rocket.
SKS Rifle
Several Viet Minh soldiers and NVA soldiers use SKS rifles during intro sequence and during the Battle of Ia Drang.
A Viet Minh soldier during the intro sequence and a Vietcong soldier later on can be seen using Karabiner 98k rifles. It should be noted that acording to one of the Armorers of the film, Steve Karnes, the Kar98ks used in the movie came from Israel and were chambered to 7.62x51mm NATO.
M1A1 "Bazooka"
A Viet Minh soldier uses an M1A1 "Bazooka" with a modified rear sight to destroy a French jeep during the intro sequence. While it seems that a Viet Minh soldier using a Bazooka could be an anachronism, the French army widely used the M1A1, M9A1 "Bazookas" and M20 "Super Bazooka" during the Indochina War. The Viet Minh widely used scavanged French weapons during the Indochina War, and the PAVN and Vietcong also widely used them during the Vietnam War.
Degtyaryov DP-28 Machine Gun
In the scene where the men of the 1st Cavalry Division perform a bayonet charge against the NVA position (an event which actually didn't happen in real life), a small crew of PAVN soldiers man a DP-28, a varient of the Soviet Degtyarov light machine gun.
Type 67 Grenade
A Chinese Type 67 hand grenade is thrown at the 1st Cavalry Division's position.
RPD Light Machine Gun
During the Battle of Ia Drang, one PAVN soldier can be seen carrying an RPD light machine gun.
ZB26 Light Machine Gun
A ZB26 Machine Gun is used by a Viet Minh machine gunner during the opening sequence of the film set during the Indochina War. Acording to Steve Karnes, the movie's Armorer, the ZB26 used in the movie was sold to the Chinese and converted to 7.62x39 later in its life. It also has Chinese characters on the side of the receiver. Another one is used by an Vietcong fighter during the Battle of Ia Drang.
MG34 Machine Gun
When the American Soldiers charge the NVA position, a two man crew of NVA soldiers man an MG34 machine gun before they get killed by the Huey helicopters. One NVA soldier also mans another MG34 in the same scene.
Fake DShK Heavy Machine Gun
A fake DShK heavy machine gun is seen manned by an NVA machine gun team in the final battle before being wasted by the Huey helicopters. The DShK seen in the film is actually an Browning M2HB machine gun mocked up to look like a DShK.
Browning Hi-Power Pistol
During the Intro of the Movie set during the Indochina War, a French Officer uses his siderarm, a Browning Hi-Power, to kill several Viet Minh soldiers before being killed himself. The use of the Browning Hi-Power pistol by the French Army in the movie is an error. The armorers couldn't get French MAB pistols and since Hi-Powers were at the region the armorers used those instead.
M34 White Phosphorous Grenade
In one scene, a wounded NVA soldier throws an M34 White Phosphorous grenade (Nicknamed "Willy Pete" by US Military personel) at Sergeant Forrester, severely wounding him.
Remington 870
In a deleted scene, Bungum's wife uses a Remington 870 to shoot skeet. The version used is the hunting version.
Note: The quality of the screencaps are low due to the fact that the scene was deleted.
Notes
There are several errors also in the uniforms of French troops:
No lieutenant from "troupes de Marine" (2 golden horizontal stripes on bleu) whould have a white kepi (Kepi blanc for Foreign Legion soldiers only, excluding NCOs and officers)
The red berets are worn the wrong way (Insigna on the right in France for all the Army. Only exception French Navy Commando green berets)
Insigna on the red berets are wrong (infantry instead of paratroopers)
Sorry, not hardware but military exactitude as well.