Use Metal 2 for: Adjustment Cylinder 1 and 2, 
Adjustment Piece, Buttstock, Stock Foundation 1 and 2, Rifle Stock,
Rifle Barrel and Rifle Barrel End, Rifle Bolt


Use Bolt Texture for: Bolt


Use Metal 3 for: Rifle Bolt Handle, Safety, Bullet Chamber, Scope Rail, Trigger Guard,
Trigger


Use Metal 4 for: Adjustment Thread, Screw 1 and 2