A Heckler & Koch UMP is seen in the hands of Colonel Everett Young (Louis Ferreira) during the attack on Icarus base. In Episode 6 Water, 1st Lt. Matthew Scott (Brian J. Smith) used Young's UMP to shoot at ice to harvest for water. The weird part is the sound effect they use when fired is the P90. According to the video on the discussion page, the weapon is confirmed to be an UMP .45 due to the armorer saying it carries a 27 round magazine.
Heckler & Koch G36K
Lieutenant Matthew Scott and Greer are seen using the H&K G36K, and sometimes switches between dual and single optics. So far this is the most visible weapon in all the trailers and promos in the hands of all other military personnel so far aside from the M4. These could be the new primary weapons used in the series. They all appear to only have the Export Optical sights. Colonel Young later on used one as a crutch.
M4A1 Carbine
What appears to be M4A1s are in the hands of the other military personnel aside from G36Ks. The M4s seen on the show have included a mix of genuine Colt M4A1s and Olympic Arms K3B-FTs (recognizable by their tall flattop receivers and "Stowaway" pistol grips).
Special
Beretta 92FS
The Beretta 92FS are seen in the hands and holsters of Lieutenant Scott, Lieutenant Johansen and Sergeant Greer
Para-Ordnance P-14
A Para-Ordnance P-14 is used by Colonel Young seen clearly in a production still for Episode 12 of season 1. Presumably the same gun used by Joe Flanigan in Stargate Atlantis since the same armorers are used for Universe.
M136 AT-4
Seen in the first episode of the series and again misused as an anti-air missile launcher. What? They couldn't get a stinger like in episode 1 of SG-1?
As we've seen in Stargate SG-1, the Lucian Alliance also uses the Kimel AP-9 pistols. We see them in episode 19.
Norinco QBZ-97
The standard assault rifle of the Lucian Alliance that appeared in episode 19. This is confirmed as it's filmed in Canada and recently declared assault rifle (automatic) as its somehow possible to convert to automatic according to Canada's national Police RCMP led to the previous owner either surrendering for destruction or sell it to film industry.
Vektor CP1
Commander Kiva's (Rhona Mitra's) gun appears to be a Vektor CP1, which has been shown previously as the main sidearm for Lucian Alliance officers.
Custom SVI 1911
Kiva gives Telford a sidearm that appears to be a custom made 1911. It looks to have a grip that same consistency as that of a Strayer Voigt Infinity 1911. As of now, there are no clear shots of the weapon.
It is one of the "Timecop" Taurus pistols. They get used a lot on the Stargate shows.
No it is not. The grip looks nothing like a Taurus pistol Excalibur01 03:59, 27 August 2010 (UTC)
AKS-74U
AKS-74U were seen among the primary weapons of the Langarans.
Walther P38
Lt. Scott impersonating a Langaran Captain, drew a Walther P38
Gatling gun
What appears to be a Gatling Gun as a mounted weapon in episode 15 of season 2.
KGP-9
A cosmetically-modified version of this submachinegun was seen in episode 15 of season 2. It was previously seen in another SyFy Channel production, Caprica.