Crawford (Chris Pedersen) is briefly seen using what appears to be an original M16 as it lacks a forward assist. It could also be an AR-15/SP1 rifle, but since he is not seen firing it, it is unknown.
M16A1
Soldiers of the 1st Platoon, Bravo Company, 25th Infantry Division "Tropic Lightning" use M16A1s, most commonly seen in the hands of Pvt. Chris Taylor (Charlie Sheen). Also using the M16A1 are Big Harold (Forest Whitaker), Manny (Corkey Ford), Francis (Corey Glover) and Sgt. Red O'Neill (John C. McGinley).
Colt Model 653P
Sgt. Elias Grodin (Willem Dafoe), SSgt. Robert Barnes (Tom Berenger), and Lt. Wolfe (Mark Moses) are armed with Colt Model 653P carbine assault rifles, noted by their rounded forward assists an 14.5" barrels, as the 653Ps were 653 export models sent to the Philippines. They were probably meant to stand in (albeit poorly) for the XM177E1 or E2. It is thus anachronistic to see these in the movie, as they were not used during the Vietnam war.
Norinco Type 56
The Norinco Type 56 is the weapon of choice of the Vietnamese troops, many of which feature "pig-sticker" under folder bayonets. They are noted as Chinese Type 56 rifles based on their hooded front sights. Only the milled receiver variant of this rifle was actually used during the war. Towards the end of the film, both Sgt. Robert Barnes (Tom Berenger) and Pvt. Chris Taylor (Charlie Sheen) are seen using these rifles, picked up from dead Vietnamese soldiers.
Machine Guns
M60 machine gun
The M60 machine gun, affectionately known in Vietnam as "The Pig", is fired primarily by King (Keith David) in the film. As was typical in Vietnam, the M60 is typically manned by two men, a gunner and an assistant gunner who "feeds" the ammo.
Browning M2HB
A Browning M2HB .50 cal is seen mounted on for use on an M113 Armored Personnel Carrier after the final stand.
Shotguns
Remington 870 Wingmaster
Bunny (Kevin Dillon) uses a Remington 870 Wingmaster shotgun with open blade sights throughout the film.
Sidearms
M1911A1
The M1911A1 is the standard sidearm for all of the NCOs and Officers in the film. It is most prominently seen used by Sgt. Elias (Willem Dafoe) when he does tunnel rat duty and SSgt. Barnes (Tom Berenger) when he uses it to threaten a little girl in the Village to get her father to talk.
Launchers
M72 LAW
An M72 LAW is seen strapped on top of Pvt. Chris Taylor's (Charlie Sheen) pack. It is also seen used by SSgt. Robert Barnes (Tom Berenger) during the final stand.
M79 grenade launcher
While never seen used in the film, the M79 grenade launcher is carried by several soldiers during the film, including Tubbs (Andrew B. Clark), a member of Red's squad.
B-40
Several NVA soldiers are armed with B-40's, a Vietnamese copy of the RPG-2.
Grenades
M26 "Lemon" hand grenade
M26 "Lemon" hand grenades are seen several times as the standard issue grenade of the members of 1st Platoon.
M34 White Phosphorous Grenade
Huffmeister (Robert 'Rock' Galotti) is seen throwing an M34 White Phosphorous grenade (also called "Willy Pete" - slang for White Phosphorous) in one of the rice wells during the raid of the village. SSgt. Robert Barnes (Tom Berenger) also uses an M34 Grenade handed to him by Ebenhoch (Mark Ebenhoch) to destroy one of the underground tunnels, this time yelling "Willie Pete!" when he throws the grenade.