Cartidge case found in Nebraska

Recently I picked up a brass center fire cartridge case near Crawford, Nebraska which is marked on the base “FA” (top) and “10 02” (bottom) – this is an area where .45-.70 Springfield cartridge cases are frequently found, result of the Cheyenne outbreak of 1879. Not sure what the diameter of the base is – looks smaller than a .30-.30 to me anyhow.

Thanks for any help you can give me.

Tom–Is the case rimmed and bottlenecked. If so, it is a .30-40 Krag.