Delta Force operators in the series carry Mk 18 Mod 1 carbines with a variety of accessories. In "Soldier Ready" (S1E03), both CAPT Leland Gallo (Matt Barr) and CWO3 Nora Madani (Christina Ochoa) use the Mk 18s to provide cover. While not entirely implausible for them to do so, this would technically be inaccurate because Delta Force uses the Heckler & Koch HK416 as their standard carbine in reality.
M4A1 carbines are used by US military and CIA personnel throughout the series. A Block II M4A1 with a suppressor is seen in "Espirit de Corps" (S1E02).
A Beretta 92FS, standing in for the M9, is carried by the pilots of the 186th Special Operations Aviation Regiment "Shadow Raiders" (based on the real life 160th SOAR), notably CWO3 Nora Madani (Christina Ochoa). A Beretta also appears to be used by an operative in "Pilot" (S1E01) and "Espirit de Corps" (S1E02).
Error creating thumbnail: File missingGarwood Industries M134G, 4 flange barrel clamp - 7.62x51mm NATOError creating thumbnail: File missingGarwood Industries M134G minigun mounted on a Black Hawk in "Pilot" (S1E01). Note that the obvious CGI muzzle flash appears to be coming from the center of the barrel cluster, when the very top barrel is actually the one a minigun fires through.Error creating thumbnail: File missingThe Minigun is fired during training in "Espirit de Corps" (S1E02).
PKM
The PKM is used by various enemy fighters in the series.