diff --git a/code/modules/cm_marines/smartgun_mount.dm b/code/modules/cm_marines/smartgun_mount.dm
index 2db33c10ed46..5954a77d9cf8 100644
--- a/code/modules/cm_marines/smartgun_mount.dm
+++ b/code/modules/cm_marines/smartgun_mount.dm
@@ -1010,7 +1010,7 @@
 	name = "M2C Ammunition Box (10x28mm tungsten rounds)"
 	desc = "A box of 125, 10x28mm tungsten rounds for the M2 Heavy Machinegun System. Click the heavy machinegun while there's no ammo box loaded to reload the M2C."
 	caliber = "10x28mm"
-	w_class = SIZE_LARGE
+	w_class = SIZE_MEDIUM
 	icon = 'icons/obj/items/weapons/guns/ammo_by_faction/uscm.dmi'
 	icon_state = "m56de"
 	item_state = "m56de"