Screw commit history.

code/modules/projectiles/guns/misc/beam_rifle.dm

@@ -19,7 +19,7 @@
 	fire_sound = 'sound/weapons/beam_sniper.ogg'
 	slot_flags = ITEM_SLOT_BACK
 	force = 15
-	materials = list()
+	custom_materials = null
 	recoil = 4
 	ammo_x_offset = 3
 	ammo_y_offset = 3

code/modules/projectiles/guns/misc/chem_gun.dm

@@ -9,7 +9,7 @@
 	throw_speed = 3
 	throw_range = 7
 	force = 4
-	materials = list(MAT_METAL=2000)
+	custom_materials = list(/datum/material/iron=2000)
 	clumsy_check = FALSE
 	fire_sound = 'sound/items/syringeproj.ogg'
 	var/time_per_syringe = 250

code/modules/projectiles/guns/misc/grenade_launcher.dm

@@ -10,7 +10,7 @@
 	force = 5
 	var/list/grenades = new/list()
 	var/max_grenades = 3
-	materials = list(MAT_METAL=2000)
+	custom_materials = list(/datum/material/iron=2000)
 
 /obj/item/gun/grenadelauncher/examine(mob/user)
 	. = ..()

code/modules/projectiles/guns/misc/syringe_gun.dm

@@ -7,7 +7,7 @@
 	throw_speed = 3
 	throw_range = 7
 	force = 4
-	materials = list(MAT_METAL=2000)
+	custom_materials = list(/datum/material/iron=2000)
 	clumsy_check = 0
 	fire_sound = 'sound/items/syringeproj.ogg'
 	var/list/syringes = list()
@@ -108,7 +108,7 @@
 	desc = "A compressed air gun, designed to fit medicinal darts for application of medicine for those patients just out of reach."
 	icon_state = "dartgun"
 	item_state = "dartgun"
-	materials = list(MAT_METAL=2000, MAT_GLASS=500)
+	custom_materials = list(/datum/material/iron=2000, /datum/material/glass=500)
 	suppressed = TRUE //Softer fire sound
 	can_unsuppress = FALSE