Location of Buckshot Ammo Pickup Material and 9mm Ammo Pickup Material

I found a material in GCFScape which is known as “ammocrate_items,” however I edited it and had placed it in this directory:
C:\Program Files (x86)\Steam\SteamApps\common\GarrysMod\garrysmod\materials\models\items (as well as its VMT) but nothing had changed.

Could someone help me out here? Of course there must be another material but I can’t find it.