The Guard Post is a 2008 South Korean horror film that examines the story behind the mysterious decimation of an entire platoon located at Guard Post 506 (GP506) near the DMZ, a border between North and South Korea.
The following weapons were used in the film The Guard Post:
The Daewoo K5 pistol is seen carried mostly by Sergeant Major Noh and Staff Sergeant Yoon. It is also seen in the flashback in a fight between First Lieutenant Yoo and the medic, where Yoo uses it to shoot the medic in the head.
Assault Rifles
Dong-San K1
Dong-San K1, airsoft replica of the Daewoo K1A, is seen carried by several soldiers in the film but is never seen up close or being fired. The difference from the actual Daewoo K1A can be seen by the lack of take-down lever behind the rear-sight, square pistol grip, larger and rounder trigger guard, higher bolt placement, straight bolt-handle, and the lack of magazine fence.
Daewoo K2
The Daewoo K2 is the weapon that is shown the most in the film, and is used by all South Korean soldiers in the movie, as it is the main assault rifle of the Republic of Korea Army. The weapon is seen with both rail system and optics on and without. Almost all of the optics and rails used are manufactured by the South Korean Dong-In Optical Company.
Ja-Seng K2 airsoft replica
When the actors aren't firing blanks, they are mostly seen with Ja-Seng K2 airsoft replicas, which would be much lighter and safer for the actors to handle, and can be used without an armorer present on the set. The difference from the actual Daewoo K2 rifle can be seen by the straight bolt-handle, smaller rear-sights, awkward-shaped folding-stocks, thinner front-sights, lower bolt placement, smaller bolt, gap between the receiver and the hand guard, and the lack of swing swivels on the lower barrel.
Trivia: The Ja-Seng K2 airsoft replicas are all-plastic, scaled-down, pump-action airsoft replicas. They are known for their bad quality: lacking bolt, smaller scale, and bad details. It is quite amazing how the prop-designers of this movie improved the quality of these airsoft replicas up to this much.
Machine Guns
Fake M60
A mocked up M60 machine-gun can be seen when Corporal Kang is explaining about the North Korean GP 300 meters away to two newcomer privates. He accidentally discharges the weapon, which results in a burst of machine-gun fire from the North. Corporal Kang shows the M60 to the newcomers, calling it as the machine-gun that came out in the movie "Rambo". However, this M60 seems to be a fake M60 with front-sight taken from AR-15 series and a thick cylindrical part of the barrel sticking out of the hand guard. The gun also apparently fires from a closed-bolt position, where as actual M60s fire from an open-bolt position. It also apparently does not eject ammunition belt links when it fires. It is unsure, however, what the base-weapon of this M60 mock up is.
Grenades
K400
The K400 grenade can be seen equipped on soldiers throughout the movie. It is used at the very end scene where it is used as a booby trap that blows the entire GP506 complex. It is a South Korean made hand grenade developed in 1975, and is still in use, although in some platoons it is being replaced with the K413 hand grenade, a smaller and lighter variant of the K400 but has the same lethal range of about 10-15 meters. The design is inspired by the M67 hand grenade, although the design has changed to be more lethal and able to be thrown further, and to produce about 1,300 fragments when detonated.
Others
1/2 Pound TNT Block
The 1/2 Pound TNT Block is shown at the end sequence with the K400 hand grenade being used as a booby trap. Noh setup the booby trap so no one would exit the GP506 alive, avoiding the spread of the infection.