Theo Noble (Michael Ealy) enters in a hospital with a Glock 19 while looking for medical supplies in "Reunion" (S3E06). FBI Tech Analyst Erin Sloan (Monique Gabriela Curnen) carries a Glock 19 in "Demons" (S3E11), attempting to draw it on Tom Reyes at the end of the episode. Tom Reyes (Gbenga Akinnagbe), an FBI HRT operator, carries a Glock as his sidearm, using it to threaten Mike in "The Edge" (S3E12). Theo takes a Glock 19 from a guard in Eliza's room in "Dead or Alive" (S3E14). FBI Special Agent Gina Mendez (Valerie Cruz) is briefly seen with her Glock 19 before Theo take it in the same episode.
Glock 17
FBI Special Agent Mike Weston (Shawn Ashmore) continues to carries a Glock 17 as his chief sidearm, which he has used since Season 1. FBI Special Agent Max Hardy (Jessica Stroup) also carries the Glock. Mike and Max are armed with they Glocks to enter in the Andrew's house during "New Blood" (S3E01). In the same episode, several corpses are seen with Glocks, representing the death of some characters in the second season. FBI Special Agent Lisa Campbell (Diane Neal) is seen armed with a Glock 17 when her and Ryan travel to Philadelphia in "Demons" (S3E11).
Smith & Wesson M&P Shield
FBI Special Agent Ryan Hardy (Kevin Bacon) carries a Smith & Wesson M&P Shield as his chief sidearm for the first half of Season 3, instead his M&Pc used in Season 2. In "The Hunt" (S3E07), he replaces it with a SIG-Sauer P239. In a continuity error, Daisy (Ruth Kearney)'s Kel-Tec PF-9 is replaced by a Smith & Wesson M&P Shield in "A Simple Trade" (S3E13) and "Dead or Alive" (S3E14).
Daisy (Ruth Kearney) uses a Kel-Tec PF-9 given by Theo as her sidearm in "The Edge" (S3E12). In a continuity error it is replaced by a Smith & Wesson M&P Shield) in "A Simple Trade" (S3E13) and "Dead or Alive" (S3E14).
Assault Rifles
Colt M4A1
The FBI SWAT agents are seen using Colt M4A1s fitted with railed handguards, vertical grips and Aimpoint red dot sights throughout the series.
AKMSU
Spider (John Keating) is seen firing what appears to be an AKMSU with RIS handguard in "Boxed In" (S3E02).
Sniper Rifles
Remington 700 PSS
In "A Hostile Witness" (S3E05), Mark (Sam Underwood) is seen with a Remington 700 PSS. He fires it when tries to defend himself from Mike. Daisy (Ruth Kearney) uses what appears to be a Remington 700 PSS fitted with an ACOG scope to cover Theo in "A Simple Trade" (S3E13).
Kel-Tec RFB Carbine
Several of Eliza's men are armed with Kel-Tec RFB Carbines to cover the meeting in "The Edge" (S3E12).
Shotguns
Remington Model 870
In "Reunion" (S3E06), Theo (Michael Ealy) borrows a Remington 870 from his internet friend and uses it later in a bank.