Carrie (Claire Danes) holds a M1911A1 style pistol outside the embassy compound for protection in "Krieg Nicht Lieb" (S4E11).
Beretta 92FS
A Beretta 92FS is seen pulled by CIA Chief of Station Sandy Bachman (Corey Stoll) in "The Drone Queen" (S4E01). Marines guarding the Embassy also appear to carry the Beretta in "There's Something Else Going On" (S4E09).
Beretta 92
In "13 Hours in Islamabad" (S4E10), the Beretta 92 appears to be the pistol used by a US Marine.
Glock 17
CIA Officer Peter Quinn (Rupert Friend) uses a Glock 17 in Season 4's premiere "The Drone Queen" (S4E01).
TT-33
Saul (Mandy Patinkin) holds a TT-33 style pistol in "Halfway to a Donut" (S4E08).
Rifles
AKM
The AKM, AK-47, and its other variants are widely seen in use by both the Pak Army as well as the Taliban and other various nefarious forces.
Heckler & Koch G3
What appear to be the South African variants of the Heckler & Koch G3 are seen occasionally carried by Pakistani Army soldiers.
M4A1
The Colt M4A1 is seen carried by CIA guards as well as embassy guards in Season 4's premiere "The Drone Queen" (S4E01). US Special Forces also are armed with the carbine in "There's Something Else Going On" (S4E09).
Mosin-Nagant
(...) a Mosin Nagant Rifle with the stock and handguard cut down to make the weapon resemble an "Obrez" sawed-off version, which is fitted with modern tactical accessories; it is shown with a suppressor, railed handguard, and a folding stock with a pistol grip.
(I haven't seen the show, please give this a proper description)