Deputy US Marshal Raylan Givens (Timothy Olyphant) carries a Glock 21 as his sidearm for the majority of the series. This is confirmed in the 2012 Glock Autopistols Magazine in the article "Box Office Glocks". In "The Hammer" (S1E10), Raylan tells Judge Reardon that he carries a "45. Glock".
Glock 17
Nearly all of the other US Marshals in the series carry full size Glocks as their sidearms as well including Chief Deputy Art Mullen (Nick Searcy) and Deputy Marshal Tim Gutterson (Jacob Pitts). FBI agents also carry Glocks, notably in "The Collection". In some episodes, the Glock seen carried by Deputy US Marshal Raylan Givens (Timothy Olyphant) appears a Glock 17. There is one promotional still of Raylan pointing his Glock just to the left side of the frame and the "9x19" can be easily read on the slide. Later in the episode, a couple of Glock 17s can be seen in the trunk of Chief Mullen's SUV, when he reaches to collect some weapons and ammo to confront Crowder's two "fat" Neo-Nazi thugs.
Glock 19
Tommy Bucks (Peter Greene) pulls a Glock 19 out from under a table when he is confronted by Raylan at the beginning of the premiere episode "Fire in the Hole" (S1E01). Later in the episode, Boyd Crowder (Walton Goggins) uses what appears to be a Glock 19 to dispatch a suspected informant.
Glock 26
The Glock 26 appears to be Raylan's backup weapon. Throughout the series, he is seen carrying it in the back of his waistband. In "Riverbrook" (S1E02), Raylan pulls the compact pistol out after being confronted by an escaped prisoner. The Glock 26 also appears to be the sidearm carried by Deputy Marshal Rachel Brooks (Erica Tazel).
Beretta 92FS
A Beretta 92FS is held by Joe (Brian Goodman) in "Long in the Tooth" (S1E04). In "Blind Spot" (S1E07), Sheriff Hunter Mosley (Brent Sexton) carries the Beretta that is later held by Raylan Givens (Timothy Olyphant). Also used by Boyd Crowder (Walton Goggins) as his sidearm for the latter half of season 1.
Colt 1911A1 (Nickel)
Boyd Crowder (Walton Goggins) carries a nickel plated Colt M1911A1 later in the premiere episode "Fire in the Hole" (S1E01). A blued 1911 with wood grips is also seen in the episode "The Collection" and is held by Greg Davis.
Colt Officer's Enhanced Mark IV
Raylan Givens carries a Custom Colt Officer's Enhanced Mark IV pistol after arriving in Kentucky in "Fire in the Hole" (S1E01). The best view of it can be seen when he does a one-handed brass check on it in the motel room before leaving to Ava's. It appears to have an added beveled mag well, 3 hole combat trigger and Novak sights.
Heckler & Koch USP Compact
In Season 1's finale "Bulletville" (S1E13), one of Bo Crowder's thugs holds a Heckler & Koch USP Compact on Raylan. When the tables quickly turn, Raylan kills the thug and then dual-wields the compact along with his Glock in a shootout as he retreats into the cabin with Boyd. Ava Crowder is then seen using it in the final gunfight.
Luger P08
In "The Collection" (S1E06), a Luger P08 is seen in the hands of Owen Carnes (Peter Jason).
SIG-Sauer P226
In "Fire in the Hole" (S1E01), Chief Deputy US Marshal Art Mullen (Nick Searcy) uses a SIG P226 during the gunfight against Crowder's two "fat" Neo Nazi thugs. In later episodes (i.e. "Long in the Tooth" the gun throws some cartridges that look more like .357 SIG, must have upgraded (the reason there is a shoulder on the casings is because they are blanks, not actual ammunition. Blanks are the same shape of a regular round of ammunition that is crimped at the top. They are shaped that way so they will feed smoothly).
SIG-Sauer "Non Gun"
At the beginning of "Fire in the Hole" (S1E01), Deputy US Marshal Raylan Givens (Timothy Olyphant) is seen using what appears to be a SIG-Sauer P226 in a confrontation with Tommy Bucks (Peter Greene). Upon closer inspection, the handgun appears to be a SIG-Sauer "Non Gun" flashpaper replica. The SIG non-gun is also seen used in "The Fixer" (S1E03).
One of Crowder's thugs uses a Ruger Mini-14 GB-F in the premiere episode. He is first using it in a bank robbery then later using the Mini-14 to pin down Raylan's team.
AKM
The other Crowder thug uses an AKM first during a bank robbery then uses it to pin down Raylan's team alongside his brother. Also used by two of the Miami gun thugs sent after Raylan in the season 1 finale "Bulletville"
Remington 700PSS
In "Riverbrook" (S1E02), Tim Gutterson uses a Remington 700PSS during a standoff with Dupree.
Bushmaster XM15 "V-Match"
A Bushmaster XM15 "V-Match" fitted with an Aimpoint M68 Sight and a rear night vision scope appears to be the rifle used by Deputy Marshal Tim Gutterson (Jacob Pitts) in the premiere episode "Fire in the Hole" (S1E01).
Shotguns
Mossberg 500
In "Riverbrook" (S1E02), escaped convict Douglas Cooper (Chris Ellis) uses a Remington 870 with synthetic stock and forearm taken from a prison guard.
Mossberg 500 Cruiser
Dewey Crowe (Damon Herriman) tries to intimidate Raylan by loading a Mossberg 500 Cruiser. The shotgun is fitted with pistol grip, vertical foregrip, and has a saddle shell holder attached to the left side of the shotgun's receiver. Dewey loads two rounds in the shotgun but forgets to rack in a load, in which Raylan calls him out and says "Can you rack in a load before I put a hole through you?" Later in the episode Raylan Givens (Timothy Olyphant) takes Dewey's shotgun and fires one round to command Dewey.
Mossberg 500AT
The Mossberg 500AT shotgun is a frequently seen weapon in Season 1. Deputy US Marshals are seen carrying the shotguns during a raid in "The Fixer" (S1E03). The shotgun is also seen in the hands of local law enforcement in "The Collection" and the bartender in "Hatless". A Mossberg 500AT Cruiser is seen in the hands of Ava Crowder.
In some scenes, the various shotguns held by characters are replaced with "Non Gun" versions. The non gun is distinguished by its non-movable pump action and resembles a Remington 870.
Heavy Weapons
M72 LAW
An M72 LAW is used by Boyd Crowder (Walton Goggins) to blow up a church in the premiere episode "Fire in the Hole" (S1E01).
RPG-7
In Episode 11, Boyd purchases an RPG-7 from a Kentucky arms dealer. He refers to it as "Chinese", despite it being an original Russian model.