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).
Heckler & Koch MP5A3 with Surefire 628 dedicated forend weaponlight and safe-semi-two round burst trigger group - 9x19mmError creating thumbnail: File missingColonel Edwards (Michael Rooker) with a MP5A3 in the episode "Enemy Mine" (S07E07).Error creating thumbnail: File missingOne of Colonel Dave Dixons squad steps down from the gate as he and the others place bets on what kind of aliens they will encounter in "Heroes, Part 1" (S07E17)
Shotguns
Ithaca 37
In "Evolution, Part 2" (S07E12), a Honduran rebel uses a chopped down Ithaca Model 37 12 gauge shotgun.
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). The weapon is appearing on very few occasions in Season 7, usually relegated to be used by background extras.
This weapon is a customized Olympic Arms K23B fitted with a Bushmaster free-floating quadruple-rail forend and a Bell & Carlson thumbhole stock. It is used with an ELCAN OS3 4x28 sight and a Beta C-Mag drum magazine with a mounted vertical foregrip and a side-mounted flashlight on the accessory rail. The first appearance is in "Avenger 2.0" (S07E09). It gets its name from Major Samantha Carter, the only character who carries it. According to the DVD commentary, it was intentionally made because blanks for the P90s were becoming increasingly expensive.
Seen used by Marines, and the secrity 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.
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.
The SG-3 team uses a M82 in "Fallen" (S07E01). Unlike the other submachinegun-using SG teams, SG-3 is armed with an M82, M16, M16 with M203, and an M60. SG-3 is a Marine team tasked with providing heavy fire support for the rest of Stargate Command
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.
SG-3 uses a M224 60mm mortar in "Orpheus" (S07E04) to provide fire support during the assault on the Jaffa labor camp. Note the airman placing his hand directly on the mortar tube, ensuring a visit to the infirmary for burn treatments later.
