Smokey is correct. The multiple tiny parallel ridges inside your bullet's body grooves first start showing up about 1877... and did not become "commonplace" on bullets until the very-early 20th-Century. Those parallel ridges (very similar to the edges of US dimes, quarters, halves, and $1-coins) are called a "reeded body-groove" or a knurled cannelure.
There is a chance your bullet was made in the late-1800s, but annual statistics on bullet production indicate your find was (by far) most likely made sometime in the early 20th-Century.
Identifying it correctly without precise measurement of its diameter is difficult. If I had to guess, I'd say it is an early-1900s bullet for the Indian Wars era US Army .45 Colt metallic-cartridge revolver. (The civil war version of that pistol was 44-caliber, not .45.)