A Czechoslovakian Sa.23 Submachine Gun with a fixed wooden stock is seen in the parachute harness of a mercenary as they prepare to do a halo jump from the C-130 transport plane. It is the 23 model because it is 9mm parabellum, the later 7.62x25mm Tokarev model has a slanted pistol grip and magazine hence the ammunition. While it might be unusual for one of the mercenaries to be carrying a communist weapon during the Cold War, the design was actually sold to and adopted by South Africa during that time period.
Some may think it is a South African Sanna-77 submachine gun. The Sanna-77 was a semi-automatic SMG issued to white Afrikaan farmers during the Aparthied era as a protection weapon, however many claim that is was merely an updated Sa.24 (folding stock 9mm). This is unlikely since the Sanna-77 was only manufactured in a folding stock version.
Sa.24 submachine gun
One mercenary can be seen with the folding stock of the 9mm submachine gun. This indicates it is the Sa.24 Submachine Gun.
RSM Sandy Young (Jack Watson) uses a Sterling L2A1 submachine gun as well as several of the other mercenaries.
MAC-10
One of the members of the hit team sent to kill Shawn Finn (Roger Moore) uses what appears to be a MAC-10.
Rifles & Carbines
L1A1 SLR
There is a huge mix of all manners of FAL rifles in the film. The Mercenaries use a mix of LAR, FAL 50.00 and L1A1 SLR models. Some of them are firing semi auto and others are firing full automatic.
FN FAL|FN FAL 50.61
Some of the Mercenaries and nearly all of the Simbas (General Endoufa's crack troops) carry the FN FAL 50.61 paratrooper rifle. This is odd, since the junta's forces are being aided by the Soviet Bloc (note the Cuban and East German military Advisors), thus it would have been more likely that the junta's soldiers are issued AK47s or other Combloc weapon.
FN LAR
Col. Allen Faulkner (Richard Burton) as well as many of the Mercenaries carry the FN LAR automatic rifle (early FAL variant)
FN FAL 50.00
Hardy Krueger as Lt. Pieter Coetze uses an FN FAL 50.00 with a wooden buttstock, like many of the other mercenaries.
Custom L1A1 Battle Carbine
Ex SAS member Tosh Donaldson played by Ian Yule used a weapon that was a chopped down L1A1 SLR that was converted to full auto fire with a special single dot reflex sight and flash hider. The actor Ian Yule, was a former real life Mercenary in the Congo during the 1960s under the command of Major Mike Hoare. For many years, fans of the film assumed the weapon was a South African R1 Variant, but information directly from the actor reminds us that there was an arms embargo against South Africa during the 1970s (because of apartheid). This was a custom made L1A1 carbine that came from a UK Movie armory.
SIG SG 510
During the attack on the barracks, a Mercenary carries a StG 57/SIG SG 510 Assault Rifle. It is also seen fired in the prone position during the final firefight.
Machine Guns
Bren Gun
The Bren Gun is used by some of the Mercenaries, both in .303 and 7.62.
Vickers Gun
A Vickers Machine Gun is used by the Mercenaries in the final crossfire against the Simbas. First manned by Sgt. Jock McTaggart and then by Capt. Rafer Janders.
FN MAG-58
The FN MAG-58 is used by some of the Mercenaries and RSM Sandy Young (Jack Watson).
Fire Support
RL-83 Blindicide Rocket Launcher
Tosh Donaldson (Ian Yule) carries and uses a Belgian RL-83 Blindicide multiple times during the final firefight. Tosh's rocket launcher does not have the blast shield installed.