The SIG-Sauer P226 is the sidearm carried by Homeland Security Special Agent Cabe Gallo (Robert Patrick) in the series. Agents with the Department of Defense also are armed with the SIG-Sauer P226 in Season 2's premiere "Satellite of Love" (S2E01).
Glock 17
In Season 2's premiere "Satellite of Love" (S2E01), Gene Simmons (as himself) is seen wielding what appears to be a Glock 17 while portraying a police officer during a production. Agent Gallo tries to correct him on the proper handling of the weapon between takes.
M1911A1
In Season 2's premiere "Satellite of Love" (S2E01), a criminal wields an M1911-style pistol at the episode's beginning.