I have a 45-70 Govt. with no headstamp. The case is a coppery looking brass. The very flat copper primer 0.225 compared to 0.204 on FA loaded rounds. The head is rounded, not flat. It is a 405gr. lead bullet. There is a slight amount of botlle-necking to secure the bullet. My guess is U.S.C.Co. based on the look of the brass.
Anyone have a better ID or can confirm mine?