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).
Machine pistols with the appearance of Beretta 93Rs are seen in a number of episodes being used by US Secret Service agents, and the Trust agent Hoskins. If you look closely, you can see that they have the slide-mounted safety/de-cocker switch, whereas the 93R has it mounted on the frame. That means they're actually Beretta 92FS dressed up to resemble M93Rs (with fake forward grips and flash hiders) and probably converted to auto with drop-in units; identical guns have also appeared in Harsh Realm and I, Robot (which were both done by the same armourers who worked on this show).
The Beretta Cougar is seen in the hands of Gen. Jack O'Neill (Richard Dean Anderson) in "Full Alert" (Season 8, Episode 14) and "Citizen Joe" (Season 8, Episode 15).
Seen in the episode "Icon" (Season 8, Episode 5) and used by the main villain at the end, this pistol is in actuality a Taurus PT99AF. This prop was later seen in Stargate Atlantis as the standard sidearm of the Genii people. This prop pistol was originally produced for the movie Timecop.
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.
Seen being used by SG-3 in "Zero Hour" (Season 8, Episode 4). What's interesting to note is that while most of the other SG teams use submachine guns, SG-3 is armed with an M82, M16, M16 with M203, and an M60. They are a USMC section tasked with SAR, retrieval and Tactical Support ops. They pretty much come out to play when extra firepower is needed or another team got into a situation that they can't handle.
Seen used by Marines, and the security of Stargate Command. These are all Olympic Arms K4B rifles (same receiver style as the Colt Model 715/Diemaco C7), standing in for the M16A2.
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.
In the episode "Icon" (Season 8, Episode 5), both the human factions on the alien world uses these rifles along with their AKs. It was seen in the hands of security guards and soldiers. Daniel (Michael Shanks) also held one at the end of the episode.
Mauser Karabiner 98k rifles were commonly seen in the episode "Icon" (Season 8, Episode 5) alongside other firearms, such as the Garand, the AK, the PPSh41 etc.
Usually seen carried by the Cheyenne Mountain guards in stock footage.
Error creating thumbnail: File missingM16A1 with 30 Round magazine - 5.56x45mmError creating thumbnail: File missingNever understood why the guy on the left always seem to hold onto his M16 slung behind him, as if to keep it from swinging around. Isn't that what slinging your rifle on your back is for? The point is so it doesn't swing around and bother you.Error creating thumbnail: File missingTwo guards with M16A1 rifles in stock footage guarding the entrance to Cheyenne Mountain.
M4A1
One of the primary weapons utilized by the Stargate teams. During later seasons they are rarely seen without any attachments, mostly being equipped with flashlights, Cobray flare launchers and laser aiming modules. A small side note for the interested reader: The lower handguard on the M4 has to be removed in order to accommodate underbarrel grenade launchers like the M203 or, in this case, the Cobray 37mm Launcher.
These two guns were set up in the gate room but were never used in the 10 years the show ran for. The M2 was also used at the Alpha site in "Allegiance" (Season 6, Episode 9), but was - once again - not fired. The weapon was then seen in "Bad Guys" (Season 10, Episode 16), mounted on an APC used by the alien security forces. 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.
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.
Error creating thumbnail: File missingA Daewoo K3 "Paratrooper" model, with a chopped barrel buttstock removed to resemble an M249 Paratrooper, and with a 200 round "soft pack" magazine. Guns in similar configurations have been seen in many action films. (This picture was edited in GIMP.)
M60 Series GPMG
Seen used by Marines in a support role in several episodes and the movie Stargate: The Ark Of Truth. Some marines are carrying the M60E3 version.
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.
