CALIBRE 40 on top flat,about 1" in front of the breach with an upside down 70 on the side flat ,same location.If I do anything with it,I think i should keep it the same caliber.I think 40-70 bottle neck,I have not done a chamber cast.

According to the factory records it was shipped to New York City in 1876 with a 30" barrel and single trigger.The rifle was returned to the factory and shipped to Meacham of St. Louis,and get this,with double set trigger and 24" barrel.