The following guns were used in this movie:
M16A1
A U.S. GI firing his M16A1.
AK-47
M60
File:M60nva.jpeg During the last battle to take the hill you can see an NVA soldier using a U.S issued M60 against the American infantry, the film makers probably had no access to an RPD at the time this movie was made.
SKS
File:Sks1.jpg An NVA soldier uses a SKS to kill Gaigin and mortally wound Doc as he tries to help.
File:Sks2.jpg If you look closely you can see the rear sight is flipped up for some reason, this would make it impossible to aim the rifle.
M1911A1
M67 grenade
M26 grenade
RPG-2
M18A1 Claymore Mine
M72 LAW