The following weapons were used in the film Blood Diamond:
In the beginning of the film, Danny Archer (Leonardo DiCaprio) carries a sub-compact Glock variant, which is most likely a Glock 26 and hands it over when stopped by Rambo (Ato Essandoh). He later has it confiscated when he is arrested for smuggling diamonds into Liberia.
Heckler & Koch USP Compact
An H&K USP Compact is used by Danny Archer (Leonardo DiCaprio) throughout the film. He purchases the weapon from a dealer at a bar for a couple hundred dollars after having his Glock 26 confiscated while smuggling diamonds He uses it to kill about seven 4 rebels and many of Col. Coaztee's men. He later gives it to Solomon near the end of the film when he tells him that he will stay and hold off Col. Coetzee's men so Solomon can make his escape.
Several close-ups of Archer's USP Compact reveal that it has an exposed hammer (the Compact, unlike the full-size USP, has a spurred hammer as standard), which suggests the gun might be the P10 variant, or otherwise a specially modified weapon.
Heckler & Koch USP
Full-size Heckler & Koch USPs are carried by the South African mercenaries, notably Colonel Coetzee (Arnold Vosloo). Koetzee's USP is later picked up by Dia Vandy (Kagiso Kuypers), the son of Solomon Vandy (Djimon Hounsou).
Smith & Wesson Model 629
Captain Rambo of the R.U.F wields a Smith & Wesson Model 629 revolver when he confronts Danny and demands his weapon. There is a slight possibility the revolver could be a Smith & Wesson Model 686, however the barrel looks about 5" which would likely make it the 629 model.
Chamelot-Delvigne Model 1873
A Kamajor guerilla point a French Chamelot-Delvigne Model 1873 11mm revolver at Solomon and Maddy Bowen (Jennifer Connelly) thinking he is R.U.F. Note: The revolver may be a M1874 which is the same gun with a fluted cylinder. It isn't seen again in the movie.
Unknown (custom?) Colt CAR-15 variant
The South African mercenaries carry an unusual Colt CAR-15 variation that does not appear to be a factory-standard gun. They have the receivers of M16A2s (which would normally suggest Colt Model 725s), but they also have 10-inch barrels with GAU-5/XM177-style flash hiders. They were most likely custom-assembled for the film from the parts of various AR-model rifles. It should be noted that similar rifles can be seen in Black Hawk Down, and Bapty & Co. supplied the weapons for both this film and that one.
Besides their unusual combination of features, the mercenaries' CAR-15s also feature camouflage paint and accessories such as Surefire weaponlights and M68 Aimpoint scopes. Archer uses one at the end of the film after killing its owner, buying time for Solomon and Dia to escape before succumbing to his wounds.
Norinco Type 56-1
The vast majority of the Revolutionary United Front (R.U.F.) rebels and the Sierra Leone Army regulars are seen using Norinco Type 56-1 assault rifles (Chinese AKS-47/AKMS clones), which can be recognized by their folding stocks and hooded front sights. Archer briefly uses one to execute an R.U.F. rebel who tries to flee him on the bridge. Dia can be seen using one while participating in his first massacre as an R.U.F. guerrilla (he is also forced to use one to kill a prisoner while undergoing indoctrination).
There are also some original Russian-made AK-47s (as opposed to AKM copies or Chinese Type 56s, which are far more common in most Hollywood films) seen in the hands of R.U.F. rebels throughout the movie. Most of them are the Type III milled receiver variation, but a close-up of one of the AKs reveals that it has the stock mounting bracket of the slightly older Type II variant. The child soldier who tries to kill Benjamin Kapanay (Basil Wallace) uses one, and Archer himself wields a Type III AK-47 during the mercenaries' assault on the mine, which he uses to off many of the rebels.
Heckler & Koch G3
Many of the R.U.F. guerrillas and Sierra Leone Army soldiers are seen carrying older-specification Heckler & Koch G3s with wooden handguards & stock though without seeing the rear sight. This is quite true to real life; the G3 was standard-issue to the Sierra Leone Army for many years (though they later began purchasing Type 56 AKs from the People's Republic of China), and many fell into the hands of the R.U.F. during the civil war.
DShK Heavy Machine Gun
Throughout the film, DShK heavy machine guns are seen mounted on the R.U.F.'s "technical" vehicles.
RUF rebels regularly wield RPG-7's, particularly during the battle of Freetown. One rebel tries to shoot at Archer and Maddie's vehicle with one during the press convoy ambush, but misses.
The Sierra Leone Army uses a number of .50-caliber Browning M2 machine guns, which are mounted to many of its Land Rovers throughout the film.
Several Sierra Leone army soldiers can be seen carrying Sterling L2A1 submachine guns during the scene where Archer is arrested for diamond smuggling.
Several Sierra Leone Army soldiers can be seen with M16A2 assault rifles, and many of the South African mercenaries use them as well.
A PKM machine gun can be seen mounted in the door of the mercenaries' Mi-24 Hind gunship and is fired by one of them.
During the scene where Archer and Soloman are crossing the bridge, an RPK light machine gun can be seen leaning against a wall at the R.U.F. guard post.