Stargate SG-1 - Season 3
The following weapons were used in the third season of the television series Stargate SG-1:
The most common sidearm seen in used by the SG teams (although in real life, the M9 is the military designation for the Beretta, the prop weapons used in the show are most likely the civilian Beretta 92FS).
Heckler & Koch MP5A3
The Heckler & Koch MP5A3, almost exclusively equipped with the Surefire dedicated forend weaponlight, is the primary weapon used by all SG teams for the first few seasons. Then when the main cast and some supporting and extras switched to the P90, the MP5 became less common. Also seen in use by the Free Jaffa Nation later in the series. MP5 also makes a small comeback when we see them again in the hands of a special assault unit raiding a Trust compound. Throughout the series it is generally the case that for non firing scenes the actors carry airsoft replica MP5s with a Navy trigger group, whereas for firing scenes their weapons switch to real firearms with SEF trigger groups.
Members of the Cult of Seth in "Seth" (Season 3, Episode 2) are seen using IMI Uzi.
Notably seen in the fight against the Replicators of our galaxy in "Nemesis" (Season 3, Episode 21).
USAS-12 Assault Shotgun
This assault shotgun is seen mostly in the episodes featuring the Replicators, but actually had its very first appearance in the first episode "Children of the Gods" (Season 1, Episode 1). The USAS-12 shotguns in SG1 are newer CQ versions with a modified carry handle, no front sight and shortened barrel (sometimes with a muzzle brake).
GAU-5/A and GAU-5A/A
The GAU-5/A and GAU-5A/A were the USAF contract versions of the XM177 and XM177E2 "CAR-15" short assault rifle. The USAF Security forces used them until recently, however, most of the non firing GAU-5A/As seen in the show were simply XM177E2 "Airsoft guns". The actual GAU-5A/A carbines look like the XM177E2 but don't have forward Assist buttons.
The GAU-5 variants that appeared on the show seem to be a mix of full-auto converted Colt AR-15 SP1s and Olympic Arms K3Bs, all with chopped barrels and fake GAU-5 flash hiders installed. The converted AR-15 SP1s have the "slab-side" receiver, while the K3Bs are recognizable by their 715-style receiver (forward assist, brass deflector, A1-style rear sight) and "Stowaway" pistol grips.
Usually seen carried by the Cheyenne Mountain guards in stock footage.
Norinco Type 84S "Target" Rifle
Some of Seth's followers in "Seth" (Season 3, Episode 2) can be seen carrying Norinco Type 84S "Target" Rifles. When observed carefully, the hooded front sights can be seen, along with the less-curved 5.56x45mm magazines.
These two guns were set up in the gate room but were never used in the 10 years the show ran for. The only instance were the weapon saw actual combat was in "Forever in a Day" (Season 3, Episode 10), were it was mounted on a F.R.E.D. during the onslaught of Heru'ur´s Jaffa.
Daewoo K3 (mocked up as M249)
Contrary to popular belief, there are no real FN Minimi or M249 light machine guns used in Stargate: SG1 or its sister show, Stargate: Atlantis. The light machine guns used by the SG teams are actually Korean-made Daewoo K3s that have been fitted with M249 Paratrooper-style stocks and shortened barrels. Some of the K3s seen on the show also have RIS rails and vertical grips similar to those seen on the Mk 46 Mod 0.
Visible in one of the storage rooms used by Seth´s followers in "Seth" (Season 3, Episode 2).
M60 Series GPMG
The M60E3 version makes a brief appearance in "Forever in a Day" (Season 3, Episode 10), while two SG teams hold off Heru'ur´s Jaffa.
Cobray CM203 Flare Launcher
Seen attached to M4s and M16s. Prop wise, these were all Cobray 37mm flare launchers meant to mimic the appearance of an M203. What tips them off is the absence of a second trigger, the shape of the trigger guard, the lack of a step up in the receiver, and the cocking lever on the SIDE of the receiver.
Most commonly 'misused' as a surface-to-air missile to shoot down Goa'uld Death Gliders, however, the AT-4 is an 84mm Anti Tank Weapon. It has also been used just as a weapon to make big explosions.