I bought some similarly-marked ammo at a local gun show last year. I pulled one round, emptied out the flake powder and fired on just the primer. Even though the case was showing corrosion around the base, the primer fired perfectly. I don't know, but I suspect it's corrosive, as it smelt very different from a modern primer. Your ammo looks in much better condition than the stuff I bought.

Strangely, the primer is a berdan, but the brass case only has a single flash hole, so I could press the primer out in the usual way. The main problems for reloading are that the primer is an unusual diameter, and there's the anvil in the primer pocket.

Muzz.