Numerous law enforcement and U.S Military personal carry and use the Beretta 92FS (standing in for the M9) as their side arm through out the series.
Glock 17
Sheriff Deputies carry what is likely to be Glock 17 pistols in several episodes. Glock 17s are also carried by ASI (Agency of Strategic Intelligences) agents in Episode 12, one of which is acquired by Rich (Jay R. Ferguson). Rich later hands the Glock over to Laura Daughtery (Lake Bell) in Episode 13, a civilian in the same episode can be seen using a Glock 17 with a stainless slide.
Throughout the series, numerous U.S Soldiers can be seen with Mossberg 500 shotguns.
Ithaca 37
Jackson Holden (Austin Nichols) uses an Ithaca 37 in episode 4 when he and Laura Daughtery (Lake Bell) are stranded on his boat. Wilmington, North Carolina police officers also use Ithaca 37s in a confrontation with the creatures in Episode 13.
12 Gauge Double Barreled Shotgun
One civilian in Episode 13 can be seen using a 12 Gauge Double Barreled Shotgun. A restaurant employee also grabs a double barreled shotgun in Episode 14.
Remington 870
In Episode 13, several civilians can be seen using Remington 870s in both full stock and pistol gripped variants.
Smith & Wesson 916
In Episode 13, one civilian in the firing line appears to use a Smith & Wesson 916 shotgun.
Rifles
M4A1
U.S Soldiers seen throughout the series also carry M4A1 Carbines.
M16A2
Various U.S Military personal are seen with what appear to be M16A2 rifles. They are also seen in the hands of U.S Coast Guard personal in Episode 5.
In Episode 13, armed civilians in Wilmington, North Carolina take part in a firing line in a rather futile attempt to cull the creatures using a wide variety of handguns, revolvers, rifles, and shotguns.