Several variants of the SIG-Sauer P226 are seen in Season 3:
SIG-Sauer P226 (Stainless Slide)
In "End Run" (S3E03), Brennen (Jay Karnes) holds a SIG-Sauer P226 with a silver slide and black hammer.
SIG-Sauer P226 (Nickel)
A nickel SIG-Sauer P226 is one of the handguns that Michael fires at the shooting range at the beginning of "Signals and Codes" (S3E05). used by "Dead" Larry Sizemore (Tim Matheson), notably in "Enemies Closer" (S3E13).
SIG-Sauer P226
A SIG-Sauer P226 is pulled by Falcone (Jeff Kober) in Season 3's premiere "Friends and Family" (S3E01).
SIG-Sauer "Non Gun"
In a continuity error, Simon (Garret Dillahunt) is seen firing a SIG "Non Gun" instead of the Walther P99 he was previously carrying in "Devil You Know" (S3E16).
Beretta 92FS
Sam Axe (Bruce Campbell) continues to carry a Beretta 92FS as his personal sidearm throughout the series.
Beretta 92FS Inox
In "Good Intentions" (S3E15), Fiona is forced to disassemble and reassemble a Beretta 92FS Inox that's later held by Gabriel (Carlos Bernard).
Michael hands Nate a Beretta Cougar in "Partners in Crime" (S3E14).
Colt M1911 Series
Colt 1911 series handguns are seen numerous times throughout the series. In "Friends and Family" (S3E01), a very shiny M1911 is used by Mike's old friend Harlan. In "Shot in the Dark" (S3E07), a 13-year-old boy drops a disassembled M1911 before admitting that he plans to kill his stepfather.
Colt Python
A Colt Python is pulled by a kidnapper in "Question and Answer" (S3E02).
"Pre-B" CZ 75
In "Partners in Crime" (S3E14), Conrad (Tom Nowicki), the Polish agent pulls a "Pre-B" CZ 75 on Michael.
CZ 75BD
In "The Hunter" (S3E06), both Michael and his new "friend" John Beck (Keith Diamond) use a Czech CZ 75BD.
Desert Eagle Mark I (Stainless)
A stainless Desert Eagle Mark I is seen in "Fearless Leader" (S3E04) when Sam is being audited as proof of his trip to the Middle East.
Desert Eagle Mark XIX (Gold-plated)
In "End Run" (S3E03), Michael is seen admiring a gun engineer's collection of guns, which includes a gold-plated Desert Eagle Mark XIX.
FN FiveseveN
In Season 3's summer finale "Long Way Back" (S3E09), bloodthirsty hooligan Thomas O'Neill (Paul Blackthorne) uses a FN FiveseveN to hold Fiona hostage.
Glock 17
Glock 17's are used by Miami PD in the many instances when Mike tricks criminals into being arrested to solve his problem of the week. In Season 3, Detective Paxson (Moon Bloodgood) and Detective Lopez both carry Glock 17's. In "Question and Answer" (S3E02), Sam uses a Glock 17 while playing a corrupt detective. In "Devil You Know" (S3E16), Michael takes a Glock off a Miami PD officer and exchanges gunfire with an FBI agent.
Glock 19
In "Friends Like These" (S3E08), Natalie (Callie Thorne) pulls what appears to be a Glock 19 from the trunk of a car that has been left for her, when she is cornered by Fiona. She quips that she always tells her buyers to leave two things in any car left for her: a duffel full of cash, and a gun full of bullets.
Glock 26
After giving up his Glock 17, Sam is seen pulling a Glock 26 to set off a shootout in "Question and Answer" (S3E02).
Heckler & Koch USP Match
A Heckler & Koch USP Match is briefly seen in the hands of a gun collector, Jonathan Carver (Scott Michael Morgan) when Michael is fleeing the scene of a fake car accident in "End Run" (S3E03).
Heckler & Koch USP Compact
In "Long Way Back" (S3E09), Fiona gives Michael her USP Compact with a stainless slide which he says is a .45 caliber. He then uses it when confronting Strickler. Fiona is seen using her USP Compact in Season 2.
Heckler and Koch Mark 23
In "End Run" (S3E03), Michael is seen admiring a gun engineer's collection of guns, which includes a Heckler & Koch Mark 23.
IMI Jericho 941 (stainless)
The stainless Jericho 941 is a very common sidearm used by bad guys in the show, especially the head bad guy in various episodes. (It's almost like what the Infinity is to Heroes.) The stainless Jericho is notably seen pulled by Santora (Holt McCallany) in "Question & Answer" (S3E02), by Erik Luna (Jay Harrington) in "Shot in the Dark" (S3E07), and by Tom Strickler in "Long Way Back" (S3E09). A black Baby Eagle was used by the henchmen in "End Run" (S3E03) and in "Enemies Closer".
Jericho 941FB Compact
In "Enemies Closer" (S3E13), the drug dealer Carlos (Carlos Gomez) pulls his Jericho 941FB Compact on Michael.
Kahr K9 Stainless
In "Friends Like These" (S3E08), Sam pulls his backup Kahr K9 stainless from an ankle holster after Ex-Serbian Intelligence officer Milovan Drago disarms him of his Beretta. After firing it several times at Milovan, he later uses it in the shootout at Bennet Tash's locksmith store.
STI Edge
In "End Run" (S3E03), Michael is seen admiring a gun engineer's collection of guns, which includes a STI Edge.
Ruger Mk I
In "End Run" (S3E03), Michael is seen admiring a gun engineer's collection of guns, which includes a Ruger Mk I. Pretending to be an idiot, Michael asks if it is a ".357".
Ruger P90
In "Noble Causes" (S3E12), Sugar (Arturo Fernandez) is initially armed with a Ruger P90 when some thieves want "to go Tombstone" on him.
Smith & Wesson SW99
In "The Hunter" (S3E06), Chechik's SIG becomes a Smith & Wesson SW99 with a nickel-plated slide when he is ambushed by Michael.
The Walther P99 is a frequent handgun used in Season 3, notably by Sean Glenanne (Gideon Emery) in "Long Way Back" (S3E09) and by both Simon (Garret Dillahunt) and Michael in the Season 3 finale "Devil You Know" (S3E16). The P99 is also carried by a kidnapper in "Question & Answer" (S3E02). Along with her PPK/S, Fiona also owns a P99 that she keeps in her apartment which Michael uses when searching for an intruder in "Shot in the Dark".
Submachine Guns
Heckler & Koch MP5A3
The Heckler & Koch MP5A3 is used by a member of the Russian extraction team sent for Michael in "The Hunter" (S3E06).
The Heckler & Koch MP7A1 is a frequent weapon used in Season 3. In "End Run" (S3E03), Sam and Fiona carry MP7's when they break into Brennan's house. Fiona and her brother Sean are armed with MP7's when they attempt to kill O'Neil at his hotel in "Long Way Home" (S3E09). Sam is seen carrying an MP7 in both "Shot in the Dark" (S3E07) and "Friendly Fire" (S3E11).
Heckler & Koch UMP
The Heckler & Koch UMP is used by a member of the Russian extraction team sent for Michael in "The Hunter" (S3E06).
Intratec TEC-9
A variant of the Intratec TEC-9 series of assault pistols (either the KG-99 or the TEC-9 itself) can be seen being used by thugs in "Fearless Leader" (S3E04).
MAC-10
In "Friends Like These" (S3E08), Michael hears the bolt action of a MAC-10 being racked by Bennett Tash. Michael also mentions that the MAC-10 is very inaccurate in the hands of an amateur.
In "Noble Causes" (S3E12), Sugar (Arturo Fernandez) is armed with a Mossberg 500 with sawed-off barrel and stock when some thieves want "to go Tombstone" on him.
Mossberg 500 Persuader (Folding Stock and Door Breaching Brake)
A frequent shotgun seen used in the series is a Mossberg 500 Persuader fitted with a police folding stock, saddle shell holder, and door breaching brake.
Mossberg 590 Special
In "The Hunter" (S3E06), Beck's men are armed with Mossberg 590 shotguns as they round up the hit squad.
Mossberg 590 Cruiser
A Mossberg 590 Cruiser is held by Joey (Nicholas Galarza) as he goes to threaten his stepfather Erik Luna (Jay Harrington) in "Shot in the Dark" (S3E07).
Serbu Super Shorty
A Serbu Super Shorty is carried by Fiona while rescuing a kidnapped child in "Question and Answer" (S3E02). Fiona also carries one in "Shot in the Dark" (S3E07).
Assault Rifles
AK Rifle
In "Signals and Codes" (S3E05), AK rifles are seen in the hangar that Michael enters when meeting CIA operative Diego Garza (Otto Sanchez).
Heckler & Koch G36C
Heckler & Koch G36C rifles are carried by members of the Russian extraction team sent for Michael in "The Hunter" (S3E06). The men guarding Management (John Mahoney) are also armed with the G36C in "Devil You Know" (S3E16).
M4A1 Carbine
In "Friends & Family" (S3E01), Mike's "old buddy" and Special Forces operator Harlan (Brian Van Holt) carries an M4A1 fitted with an M203 grenade launcher, PEQ-2 IR pointer, Surefire light, Aimpoint CompM4 red dot sight, and 3X magnifier to fire into the windshield and engine block of an SUV to disable it during a snatch-and-grab op to kidnap a Venezuelan gangster.
SIG SG 552
The SIG SG 552 assault rifle is a frequently used weapon in the series. In Season 3's summer finale "Long Way Back", Mike uses a SIG rifle when he and Sam go to rescue Fiona. Mike is seen with one slung over his shoulder in "Friendly Fire" (S3E11) when repelling out a window. In "Enemies Closer" (S3E13), Mike gives a SIG with a scope attached to a drug dealer shoot up a car.
Sniper Rifles
Bushmaster XM15 "V-Match"
A Bushmaster XM15 "V-Match" fitted with a scope and bipod is used by Sam to provide cover in Season 3's premiere "Friends and Family", as well as when he and Michael go to save Fiona in the Season 3's summer finale "Long Way Back" (S3E09).
Heckler & Koch SL8-1
A Heckler & Koch SL8-1 fitted with a laser sight is used by Sean Glenanne in "Long Way Back" (S3E09).
Remington 700 AICS
One of the preferred sniper rifles used by Fiona is the Remington 700 AICS.
Heavy Weapons
Browning M2HB
In "Good Intentions" (S3E15), a Browning M2HB is seen being prepped by Mason Gilroy (Chris Vance) to be used for a particular job.
M60
In "End Run" (S3E03), an M60 is briefly seen as Sam and Fiona infiltrate the home of Brennan (Jay Karnes).
M203 Grenade Launcher
In Season 3's premiere "Friends and Family" (S3E01), Harlan (Brian Van Holt) is armed with an M4A1 with an M203 grenade launcher attached underneath.
Other
M12 Flash Bang Grenade
Members of a Russian extraction team deploy an M12 Flash Bang grenade when kidnapping Michael in "The Hunter" (S3E06). Michael is then seen using the grenade to create an IED.