Jack Bauer (Kiefer Sutherland) uses a Heckler & Koch USP Compact, chambered in 9x19mm Parabellum, throughout the whole series of Season 6, in both sound suppressed and unsuppressed form.
TRIVIA: There were only two H&K USP Compacts used by Kiefer Sutherland through the entire run of the series. This was because Kiefer is a method actor and did not like to change props. He only wore 3 real kevlar bullet proof vests through out all 8 seasons. (IMFDB thanks The Golden Closet for providing the documentation on this gun.)
Curtis Manning (Roger R. Cross) uses a Glock 17, chambered in 9x19mm Parabellum. Also used by Mike Doyle (Rick Schroder) until he switches to the Beretta Px4 Storm. Also used by CTU Field Agent Turner, which later falls in the hands of Bill Buchanan (which he uses during the season finale).
The lead mercenary Zhou (Ian Anthony Dale) uses a Glock 17 modified to fire on full auto while breaking into CTU in "3:00 a.m. – 4:00 a.m." (S6E22). The handgun also is fitted with a stainless slide, and a 33 Round magazine.
Ahmed Amar (Kal Penn) uses a Beretta 92FS while taking the Wallace family hostage, notably in "9:00 a.m. – 10:00 a.m." (S6E04). This pistol was also used by both Phillip Bauer (James Cromwell) as well as some of his men, notably in "12:00pm – 1:00pm" (S6E07) and during the Season 6 finale "5:00am - 6:00am" (S6E24). Jack also uses a suppressed 92FS when in Heller's house in "5:00am - 6:00am" (S6E24).
Mike Doyle (Rick Schroder) uses a Beretta Px4 Storm, chambered in .40 Smith & Wesson (14 rounds), throughout the later part of Season 6,it is quite clearly seen in the CTU Truck, in both suppressed and unsuppressed form, after pulling it from a CTU truck. Jack Bauer is also able to acquire a PX4 Storm from a dead CTU guard during the attack on CTU by the Chinese. He uses is to kill several chinese operatives.
The Makarov PM is held by Russian Embassy guards and used by Jack to kill several Russian guards at the Russian Consulate in "6:00 p.m. – 7:00 p.m." (S6E13).
Philip Bauer carries a Springfield 1911 with a custom slide that appears to say "PROFESSIONAL CAL 45". Josh Bauer (Evan Ellingson) also is seen with it.
A Walther P99 is used by one of Abu Fayed's men when Ray Wallace (Raphael Sbarge) delivers the package as well as by one who engages in a firefight in "8:00 a.m. – 9:00 a.m." (S6E03).
When Jack Bauer (Kiefer Sutherland) arrives, US Marines prepare to take aggressive action with M16A2 assault rifles if Jack doesn't cooperate during "6:00am - 7:00am" (S6E01). This is also carried by the Palmdale Prison guards during 8:00am - 9:00am (S6E03).
M4A1 rifles are the preferred armament of CTU Tac teams as well as SWAT officers. During the arrival of Jack Bauer from Chinese custody, US Marines prepare to take aggressive action with M4 assault rifles if Jack doesn't cooperate during "6:00am - 7:00am" (S6E01). Some members of the CTU tactical team use M4A1 rifles fitted with M68 sights, and tactical lights during a raid in "9:00am-10:00am" (S6E04). The CTU tactical team as well as Mike Doyle (Rick Schroder) also use M4A1 rifles with a foregrip, M68 sight, and a tactical light) in various episodes notably during the assault on the Russian embassy.
Jack picks up a dead mercenary's H&K G36C with a C-More reflex sight in "2:00 A.M. - 3:00A.M.". At one point, the rifle Jack picks up lacks the magazine. This rifle is also used by one of Abu Fayed's (Adoni Maropis) guards in 7:00 A.M. - 8:00 A.M.
One of men is seen with a custom AKMS with a chopped barrel in "9:00 a.m. – 10:00 a.m." (S6E04). It's possible that this is the same custom rifle seen in Terminator 3.
Error creating thumbnail: File missingCustom AKMS Assault Pistol with folded stock 7.62x39mm. The Custom rifle has parts from the Norinco Type 56 and the AKMS. In reality, these rifles don't interchange parts, but it was possible since the gun is massively customized and practically rebuilt from scratch.Error creating thumbnail: File missingAn AKM is held by one of Fayed's men in "9:00 a.m. – 10:00 a.m." (S6E04).
The Heckler & Koch MP5K-PDW is used by several CTU Tactical members during the rescue of Morris O'Brian in "1:00 p.m. – 2:00 p.m." (S6E08). Two of Zhou's mercenaries use the Heckler & Koch MP5K-PDW with their stocks unfolded in "3:00 a.m. – 4:00 a.m." (S6E22).
Jack Bauer (Kiefer Sutherland) uses a Heckler & Koch MP7A1(which he acquired from the trunk of a CTU vehicle) at the oil refinery shooting oil barrels during his aerial assault then hands the gun off to Bill Buchanan (James Morrison) during the rescue of Josh Bauer (Evan Ellingson) in the Season 6 finale "5:00 a.m. – 6:00 a.m." (S6E24).
In "7:00 a.m. – 8:00 a.m." (S6E02), the US Marines' AH-1W Super Cobra is prominently featured with its three-barreled version of the GE M61 Vulcan, the General Dynamics M197 Vulcan. Just as in Season 4, the Cobras seen here are the real thing, as the production was able to secure cooperation from the United States Marine Corps and the Department of Defense.