Did as much as I can with adding more GATO branding.

code/modules/projectiles/guns/ballistic/automatic.dm

@@ -251,8 +251,8 @@
 	fire_delay = 1
 
 /obj/item/gun/ballistic/automatic/ar
-	name = "\improper NT-ARG 'Boarder'"
-	desc = "A robust assault rifle used by Nanotrasen fighting forces."
+	name = "\improper GATO-ARG 'Boarder'"
+	desc = "A robust assault rifle used by GATO fighting forces."
 	icon_state = "arg"
 	item_state = "arg"
 	slot_flags = 0

code/modules/projectiles/guns/ballistic/launchers.dm

@@ -76,7 +76,7 @@
 
 /obj/item/gun/ballistic/rocketlauncher
 	name = "\improper PML-9"
-	desc = "A reusable rocket propelled grenade launcher. The words \"NT this way\" and an arrow have been written near the barrel."
+	desc = "A reusable rocket propelled grenade launcher. The words \"GATO this way\" and an arrow have been written near the barrel."
 	icon_state = "rocketlauncher"
 	item_state = "rocketlauncher"
 	mag_type = /obj/item/ammo_box/magazine/internal/rocketlauncher

code/modules/projectiles/guns/energy/energy_gun.dm

@@ -39,7 +39,7 @@
 
 /obj/item/gun/energy/e_gun/old
 	name = "prototype energy gun"
-	desc = "NT-P:01 Prototype Energy Gun. Early stage development of a unique laser rifle that has multifaceted energy lens allowing the gun to alter the form of projectile it fires on command."
+	desc = "GATO-P:01 Prototype Energy Gun. Early stage development of a unique laser rifle that has multifaceted energy lens allowing the gun to alter the form of projectile it fires on command."
 	icon_state = "protolaser"
 	ammo_x_offset = 2
 	ammo_type = list(/obj/item/ammo_casing/energy/laser, /obj/item/ammo_casing/energy/electrode/old)