Identify this tin can please
 

I bought a pair of these from Dennis Walker's auction a year or so back. Aside form the markings on the lid, there is nothing that identifies what they are for. If I had to guess, I would say they are for charge bags, but I am just guessing and no idea what gun they would be for. Can anyone help?
They are just under 8" round and 4-1/2" high. The can lid is embossed with "No396" and "OC/C44"