That's an early UMC (Union Metallic Cartridge Co) shell. 3 1/4 Dram equivilent of Hercules EC smokeless powder and 1 1/8 ounces of 00 Buck.

I don't think there's any way to tell if was intended for the military. In general, shot-shells were purchased from commercial manufacturers and you'd need the box to see if they were military. Being loaded with EC powder and having a UMC headstamp it's more likely an early 20th Century shell.