The SIG-Sauer P226 is the preferred sidearm of Red Troop and is used throughout the series. It is frequently seen holstered whenever the team are wearing their counter terrorist gear, but is normally only used for undercover work.
Beretta 92FS
Haley (Matt Rippy) uses a Beretta 92FS with and without a suppressor in "Slow Bomb" (Episode 4.5).
Browning HP
A Browning Hi-Power was prominently used by Henno (Ross Kemp) in "Changing of the Guard" (Episode 4.1). Patrick (Sam Callis) can also briefly be seen with a Browning during a mock terrorist assault in "Slow Bomb" (Episode 4.5).
Becca (Heather Peace) carries a Glock 19 whilst conducting undercover surveillance in "Violent Solutions" (Episode 4.4).
Beretta M1934
Hassan (Alex Caan) can briefly be seen with a Beretta M1934 in "The Dividing Line" (Episode 4.3).
Taurus PT92
In "Violent Solutions" (Episode 4.4) the gang leader Monty (Robbie Gee) carried a Taurus PT92AFS.
Desert Eagle
A nickel plated Desert Eagle of some sort can be seen being carried by one of the gang members in "Violent Solutions" (Episode 4.4). It is never shown clearly, so the particular model cannot be identified.
An unidentified pistol can be seen being carried by a member of Red Troop in "Slow Bomb" (Episode 4.5) whilst posing as a terrorist.
Submachine Guns
Heckler & Koch MP5A3
The standard-issue weapons for the SAS unit Red Troop in the TV show are Heckler & Koch MP5A3 submachine guns, which are always seen with Surefire fore ends and tactical flashlights as well as the SEF-style lower receiver. These weapons are typically used in Red Troop's domestic hostage rescue missions.
The other SAS unit, Blue Troop, also use identical weapons, as do many Metropolitan Police SO19 (now CO19) officers throughout the show.
Heckler & Koch MP5KA1
A Heckler & Koch MP5KA1 is used by Slava (Daniel Betts) in "Changing of the Guard" (Episode 4.1). The MP5KA1 is a version of the original MP5K designed for concealed carry (it lacks the H&K diopter sights in order to avoid getting snagged on clothing when being drawn quickly from beneath a jacket).
IMI Uzi
IMI Uzis are used by government forces, guerillas, and US close protection officers in "Charlie Bravo" (Episode 4.2).
Mini Uzi
The Mini Uzi machine pistol appears in several episodes being used by terrorists.
Walther MPL submachine guns are used by government forces, guerillas, and US close protection officers in "Charlie Bravo" (Episode 4.2).
Assault Rifles
L85A1
Regular British forces throughout the show are seen wielding L85A1 service rifles. They are never operationally carried by Red Troop, like their real life SAS counterparts, however they are used for ceremonial purposes. Since Ultimate Force was filmed after 2000 the use of L85A1s is anachronistic, having been replaced by the L85A2 variant by Heckler & Koch.
CAR-15s are used commonly by the SAS in the show, almost always fitted with a Cobray CM203 grenade launcher. The "Stowaway" pistol grip and the areas of black tape covering logos on the lower receiver suggest that this weapon is built from an Olympic Arms rifle, most likely a K3B.
Colt M16 (SP1)
IMI Romat
Valmet M62
AKM
Colt M16A1
Zastava M70B2
AK-74 (Mocked up)
Heckler & Koch G36C
One of the weapons in the arms stash in Episode 3.2, "Never Go Back" is a Heckler & Koch G36C which is briefly handled but never used.
Heckler & Koch G3A3
Heckler & Koch G3A4
Colt M4A1
Colt M4A1 or something similiar. We start seeing these in season 4.
AK-74
IMBEL M964
FN FAL LAR
L1A1
HK33A2
Sniper Rifles
Accuracy International L96A1
Whenever Red Troop requires sniper support, the snipers are typically armed with Accuracy International L96A1 rifles in 7.62x51mm NATO.
Unknown Heckler & Koch G3 Sniper Variant
BMS Snicam
Seen in season 4, episode 1 "Changing of the guard"
Machine Guns
FN Minimi
Red Troop is frequently seen using the FN Minimi for support during missions overseas.
L7 GPMG
RPD
Seen in season 4 episode 1, "Changing of the Guard"
KPTV
Para Minimi
M60
Browning M2
A Browning M2 was seen in episode 4.2 "Charlie Bravo".
Seen in the first episode of the series, "Killing House", one of the bank robbers had this weapon.
In the Episode Natural Selection, the rogue paratrooper that tried to prevent Candidates from finishing SAS Selection used this to fight and injure other Paratroops.
Mossberg 500 Cruiser
Heavy Weapons
Cobray CM203
Red Troop's M16s and CAR-15s are often fitted with what appear to be M203 grenade launchers. However, a close inspection of the receivers reveals that they are actually the look-a-like Cobray CM203 37mm launchers which are often used to substitute for the M203 in many films and TV shows.
LAW 80
Or more like a mock up of this weapon seen in episode 4.4 "Violent Solutions"