Need ID on button or badge

[csachipper]

I found this badge or button last spring. I found it at a campsite where we found both Union and Confederate items. It shows an ammo pouch which is in front of a musket, artillery sword and bugle. Any help is appreciated. Thanks for looking.

 

[Carolina Tom]

Dating Metallic Insignia: Collar Disks

Those two holes on the back make me think collar disc.