At first glance, the bullet does look like a .45-70... but the ruler below the bullet clearly shows its diameter is smaller than a .45-70 bullet's "approximately" 7/16th-inch diameter. This bullet's diameter looks to be "approximately" 3/8-inch, which could be either a .36, .38, or .40-caliber. Its length indicates it is for a rifle, not a pistol. Unfortunately I do not recognize it off the top of my head, and would have to do some research to ID it. At the moment, I think it is from the late-1800s, but might be from the early 20th-Century.
We need super-precise measurement (in hundredths-of-an-inch) of its diameter to be 100%-certain about its ID.
By the way... it is not a "4-ring" bullet. Its body has 3 grooves and a "rebated" base to fit snugly into the metallic casing's lip. The rebate is actually not a ring or groove.
