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).
Beretta 92FS Inox
The Beretta 92FS Inox appears in the episode "Absolute Power" (Season 4, Epsiode 17), carried by Daniel Jackson's bodyguards at his estate.
(Mock-up) Beretta M93R
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).
In the episode "Bad Guys" (Season 10, Episode 16) a COP 357 Derringer is used by a lowly security guard. It was never fired in the episode.
Colt M1911
Lieutenant George Hammond (Aaron Pearl) uses a M1911 as his sidearm in "1969" (Season 2, Episode 21).
Glock 17
The Glock 17 appears in several episodes, being used by various people such as rogue NID agents, Dr Tanner's associate in the episode "Point of No Return" (Season 4, Episode 11) Adrian Conrad's bodyguards, Harry Maybourne, and Major Carter.
Jericho 941
In the episode 200 (Season 10, Episode 6), Mitchell imagined himself fighting zombies. If you forgot about this episode, yes zombies. When he was doing his last stand backing towards the activating gate, he took out a two tone Jericho 941 or the "Baby Eagle", as director Martin Wood refers to Mitchell's handgun correctly in the DVD commentary.
Luger P08
A Luger P08 is used by a member of the Lucian Alliance and later Teal´C in "Camelot" (Season 9, Episode 20).
Makarov PM
Mercenaries disguised as Russian soldiers use Makarov PMs in "Desperate Measures" (Season 5, Episode 11).
Rossi Model 971
In "Memento Mori" (Season 10, Episode 8), Vala (Claudia Black) disarms a shoplifter who is using a Rossi Model 971.
Ruger P89
A stainless steel Ruger P89 is used by one of Dr. Tanner's associates in the episode "Point of No Return" (Season 4, Episode 11).
Smith & Wesson Model 10
First seen in "1969" (Season 2, Episode 21) as the sidearm of Air Force security personnel. In the episode "Icon" (Season 8, Episode 5), Jared Kane (Matthew Bennett) was seen using a Smith & Wesson Model 10 as his side arm.
Smith & Wesson 5906
A number of Smith & Wesson 5906 pistols are seen in the episode "Wormhole X-Treme!" (Season 5, Episode 12) being used by the group of extraterrestrial humans led by Peter Tanner.
SIG-Sauer P226
The SIG-Sauer P226 is used in the episode "Desperate Measures" (Season 5, Episode 11) by Major Carter and Harry Maybourne. It was again used in the episode "Smoke and Mirrors" (Season 6, Episode 14) by one of Senator Kinsey's Secret Service Agents. It appears numerous times later on in the series as the standard-issue sidearm for NID agents.
SIG-Sauer P228
A SIG-Sauer P228 is used by Alec Colson (Charles Shaughnessy) during "Covenant" (Season 8, Episode 8) when he contemplates killing himself.
Taurus PT92
The Taurus PT92 is used in the first 12 episodes of Stargate SG-1's first season as a stand-in for the actual, firing Beretta 92FS/M9, which was apparently unavailable to the production crew until the 13th episode of the first season, "Hathor" (Season 1, Episode 13).
Dressed up Taurus PT99AF AKA Timecop gun
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.
Vektor CP1
The Vektor CP1 can be seen during the episode "Company of Thieves" (Season 10, Episode 9) in the hands of Anateo (Rudolf Martin), Netan (Eric Steinberg) and another Lucian Alliance soldier.
Walther P99
The Walther P99 is used by rogue NID agents in "Touchstone" (Season 2, Episode 14), Colonel Simmons in "Desperate Measures" (Season 5, Episode 11), and by Jack O'Neill in "Sight Unseen" (Season 6, Episode 13).
Submachine Guns
Beretta PM12S
A number of Beretta PM12S submachine guns are seen used in the same episode "Bad Guys" (Season 10, Episode 16) as the Scorpion by security guards and the police of that planet. One was also taken by Teal'c so he can dual wield it.
Cobray M11/9
One of the agents protecting Senator Kinsey in "Smoke and Mirrors" (Season 6, Episode 14) is seen with a Cobray M11/9.
FN P90 Personal Defence Weapon
The FN P90 became the most common weapon after its introduction in "The First Ones" (Season 4, Episode 8). In the episode that introduced it, O'Neill suggested the weapon because of the ammo was more penetrating than the MP5. We can assume it was just a device in the script just to bring this weapon into the fold, which is rare since there aren't that many series that actually brings up a weapon for the sake of the plot, which the series has for the rest of the show. This is the weapon that is identified when anyone thinks of of the Stargate series. The series probably picked this weapon for its futuristic look, something unique from the other weapons at the time and probably because the budget allowed for the expensive ammunition that comes with a P90, even blanks would cost a lot of money. Dan Shea, series stunt coordinator (1997-2007), has stated one reason the P90 was chosen is that it ejects the empty brass straight down when firing; this allows positioning of actors in a scene without worrying where expended cartridges will be flying. In addition, the weapon is ambidextrous in design, so both right- or left-handed shooters can handle it without problem.
In a few episodes, in the later seasons, Teal'c has been seen dual wielding this SMG, probably because he was not trained in standard practices of Earth military. However, in Stargate: Continuum, Colonel Cameron Mitchell was also seen dual wielding P90s. Also seen once in the hands of Bra'tac and the Free Jaffa. Introduced to the Free Jaffa in Season 5 episode "The Warrior". Any subsequent episode with the free Jaffa, we see these in their hands over staff weapons.
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.
Heckler & Koch MP5K
MP5Ks are used by NID agents in "Chain Reaction" (Season 4, Episode 15) and members of The Trust in "Memento Mori" (Season 10, Episode 8).
H&K MP7
SG-1 were first seen using MP7s when impersonating non-Earth humans, rather than their more distinctive P90s. Since then, the MP7 has not been seen in used by the SG teams and only a handful of extras are seen holding them. In the episode "200" (Season 10, Episode 6), Mitchell, in his own imagination, was seeing dual wielding MP7s with the gun's sights folded and with extended magazines fending off Zombies.
IMI Uzi
One of the east German guards in "The Gamekeeper" (Season 2, Episode 4) is seen firing a IMI Uzi at O´Neill and his team. Members of the Cult of Seth in "Seth" (Season 3, Episode 2) are also seen using them.
Kimel AP-9
The Kimel AP-9 can be seen in the episodes "Company of Thieves" (Season 10, Episode 9) and "Bounty" (Season 10, Episode 15) as one of the primary weapons of the Lucian Alliance foot soldiers.
M1 Thompson
Seen used by Mitchell (Ben Browder) in the movie Continuum is an M1 Thompson noted by cheap rear sights and side mounted bolt, but Mitchell went back in time and used this gun in 1939, which makes it a major continuity error since the M1 and M1A1 weren't made until 1942 when the US entered WWII. Guess they didn't care, didn't know, or where just trying to impersonate a M1928A1, which looks similar.
MAC-10
In the episode "Off the Grid" (Season 9, Episode 16), Worrel (Vince Corazza) uses a MAC-10 for a couple of scenes before taking one of SG-1's MP7s. The barrel attachment is of a similar build to the one used on Blade and Blade II.
Sa. Vz.61 Skorpion
Alien museum security personnel use Skorpions in "Bad Guys" (Season 10, Episode 16).
Steyr SPP
A thug in the episode "Off the Grid" (Season 9, Episode 16) holds a modified Steyr SPP pistol with factory rails, Aimpoint sight and custom flash hider.
Shpagin PPSh-41
Seen at the end of the episode "Icon" (Season 8, Episode 5) in the hands of religious fanatics and their leader Soren (James Kidnie).
Micro Uzi
Seen being used by Secret Service agents in "Divide and Conquer" (Season 4, Episode 5) and by NID agents in "Chain Reaction" (Season 4, Episode 15).
Shotguns
Armsel Striker
The Armsel Striker should not be mistaken for the Milkor MGL. The difference is the obvious difference in ammunition and the charging handle on the side of the weapon(which the MGL lacks). It is a shotgun presumably using fragmentation grenade shotgun rounds.
Cobray Street Sweeper
Seen in the hands of Cameron Mitchell (Ben Browder) in "Stronghold" (Season 9, Episode 14) during the attack on Ba´al´s Ha´tak.
Franchi SPAS-12
Notably seen in the fight against the Replicators of our galaxy in "Nemesis" (Season 3, Episode 21) and in "Menace" (Season 5, Episode 19) in the hands of O´Neill (Richard Dean Anderson), Teal´C (Christopher Judge) and various Airmen.
Ithaca 37
In the Episode "Evolution, Part 2" (Season 7, Episode 12), a Honduran rebel uses a chopped down Ithaca Model 37 12 gauge shotgun.
New Haven Model 600AT
In "Uninvited" (Season 10, Episode 5), the general and Mitchell were seen carrying New Haven Model 600AT pump action shotguns. General Landry (Beau Bridges) is carrying a New Haven Model 600AT 12ga Shotgun with a 28" ribbed barrel.
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).
Winchester Model 120 Ranger
The shotgun that Mitchell (Ben Browder) is carrying in "Uninvited" (Season 10, Episode 5) is the Winchester Model 120 Ranger with a 28" barrel. It is chambered in 12ga. The Model 120 Ranger was a field version that was developed as a final 'variant' of the blued metal Model 1200. It was made between 1986-1989, well after the cessation of most of the Model 1200 production, but Winchester eventually ceased all production in favor of promoting their (cheaper to make) aluminum/alloy Model 1300.
Rifles
Barrett M82
Seen being used by SG-3 in "Fallen" (Season 7, Episode 1) and 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.
"Carter Special" Micro Carbine
This appears to be a customized Olympic Arms K23B with a short 7" barrel, aftermarket quadruple-rail SOPMOD accessory forend, and a modified thumb-hole stock taken from a Sterling AR-180 rifle. It is used with an ELCAN sight and a Beta drum mag with a mounted vertical foregrip and a side-mounted flashlight on the accessory rail. The first appearance is in "Avenger 2.0" (Season 7, Episode 9). It gets its name from Major Samantha Carter, the only character who carries it. We later also see it in "Heroes, Part 2" (Episode 18 of Season 7). According to the DVD commentary, it was intentionally made because blanks for the P90s were becoming increasingly expensive.
Diemaco C7/Olympic K4B
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.
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.
Heckler & Koch G3SG/1
Used in the episode "Orpheus" (Season 7, Episode 4) by O'Neill. G3SG/1 is the real name of the rifle, and a coincidence to the name of the team that used it on occasion. It's also seen briefly in the episode "Enemy Mine" (Season 7, Episode 7), when the Unas are about to attack the base camp.
Heckler & Koch G36K
Two versions of this gun were seen throughout the running of SG1. The true "K" version with the scope and the "KE" version lacking the scope.
Heckler & Koch SL8
A member of SG-15 can be seen armed with a Heckler & Koch SL8 in "2001" (Season 5, Episode 10), outfitted with a scope and bipod.
M1 Garand
First seen in "Fire and Water" (Season 1, Episode 12) in the hands of two members of the colour guard during the memorial service. 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
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.
M16A1
Usually seen carried by the Cheyenne Mountain guards in stock footage. It could also be seen during the lockdown of the mountain in the episode "A Matter of Time" (Season 2, Episode 16).
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.
Norinco Type 84S
In Stargate: Continuum, Cameron Mitchell uses a Norinco Type 84. The weapon he holds is an underfolder Type 84S. The Foreward wooden grips have been replaced with a darker wood, but the rest of the gun is obviously a Type 84, including two .223 Rem Caliber magazines taped together - 5.56mm.
Remington Model 700
A Remington 700 is used in the "The Gamekeeper" (Season 2, Episode 4). This one fitted with a bipod and suppressor. In "Smoke and Mirrors" (Season 6, Episode 14), the gunman uses a Remington model 700 with a customized breakdown and scope to shoot Senator Kinsey. Contrary to what Barret claims in the episode, a Remington 700 could be purchased at just about any sporting goods store, and the collapsible stock would not have been difficult to acquire either.
Knight's Armament Revolver Rifle
In "Smoke and Mirrors" (Season 6, Episode 14), the gunman looks at a Knight's Armament Silent Revolver Rifle at the arms dealer's warehouse. It is built around a .44 Magnum Super Redhawk revolver.
Remington 7600
A hunter in "Uninvited" (Season 10, Episode 5) is seen with a Remington 7600 rifle.
Savage Mk.IIG
Darrell's rifle in "Bounty" (Season 10, Episode 15) is a Savage Mk.IIG or some variation thereof.
SVD Dragunov
Used by a East German sniper in "The Gamekeeper" (Season 2, Episode 4) and the Russian SG team in "Metamorphosis" (Season 6, Episode 16).
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Winchester Model 62A
Vala and Darrell were shooting tin cans with these rifles from the episode "Bounty" (Season 10, Episode 15). Vala's rifle looks to be a Winchester Model 62A pump action rifle (.22lr).
(Mock-up) AKS-74U
Used in "The Tomb" (Season 5, Episode 8), these are most likely Norinco Type 84 rifles modified with a Krinkov parts kit to resemble the actual AKS-74U, a practice not uncommon in movies and television shows. Further info on the discussion page.
Zastava M70
The weapons used by the Honduran Rebels in "Evolution" Part 1 and 2 (Season 7, Episode 11 & 12) are versions of the Zastava M70. Government soldiers and zealots in "Icon" (Season 8, Episode 5) can also be seen wielding them.
Unknown hunting rifles
In "Uninvited" (Season 10, Episode 5), several hunting rifles were shown being shot and held by big game hunters.
Machine Guns
Browning M2
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 only instance were the weapon saw actual combat was in "Forever in a Day" (Season 3, Episode 10), were it was mounted on a M.A.L.P. 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.
FN M240
Used in the straight-to-DVD movie Stargate: The Ark Of Truth and visible in one of the storage rooms used by Seth´s followers in "Seth" (Season 3, Episode 2).
FN M249
Only seen once, in "A Matter of Time" (Season 2, Episode 16), utilized during the lockdown of the mountain.
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.
PKM Machine Gun
Seen utilized by the Russian SG team in "Metamorphosis" (Season 6, Episode 16).
Heavy Weapons
M18A1 Claymore
Frequently used by the SG teams in order to lay traps. Usually used in conjunction with a remote detonator, much like the C4.
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.
Cobray CM79LF 37mm Launcher
O'Neill uses a CM79LF as a 40mm grenade launcher in "The Fifth Man" (Season 5, Episode 4) to shoot down a death glider.
FIM-92 Stinger Missile
Seen twice, first in the first season opener "Children of the Gods" (Season 1, Episode 1), where it is used by a member of SG-2 to take out a glider. Secondly in "Full Circle" (Season 6, Episode 22). This is the correct weapon to use for surface to air attack unlike the AT-4 which is sometimes utilized for this purpose in Stargate SG-1.
GP-25
Seen mounted underneath the Norinco Type 84 used by Lieutenant Colonel Sergei Evanov (Raoul Ganeev) in "Metamorphosis" (Season 6, Episode 16).
M203 Grenade Launcher
What appears to be a genuine M203 grenade launcher appears in "Evolution, Part 2" (Season 7, Episode 12) mounted on an M4A1.
Mortar Unknown type
Seen in "Orpheus" (Season 7, Episode 4). SG-3 used these to lay mortar support during the assault on the Jaffa labour camp.
M136 AT-4
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.
Milkor MGL
This launcher, or a version thereof, was used by Teal'c in the episode "Death Knell" (Season 7, Episode 16) when hunting an Anubis Super Soldier.
Utilized by the SG teams. In a very memorable scene, Jack O´Neill (Richard Dean Anderson) drops two into the shield generator of a Goa´uld mothership in order to disable it during "The Serpent´s Lair" (Season 2, Episode 1).
Flashbang
Used most prominently in "Insiders" (Season 10, Episode 4) to take out the guards of one of Ba´al´s clones. The specific make is - as of yet - unknown.
Knives
Phrobis M9 bayonet
While not a firearm, an interesting fact is that the knife usually carried by Jack O´Neill (Richard Dean Anderson) is a Phrobis M9 bayonet with an OD Handle and sheath with an integrated pistol mag pouch. The most memorable scene featuring this weapon comes from the episode "Secrets" (Season 2, Episode 9): O´Neill uses it to disable Heru'ur´s Goa´uld hand-device.