As TxMike said, it is a FMJ (Full Metal Jacket) 20th-century copper-jacketed .45 caliber automatic pistol bullet. With bullets, the term "jacketed" means the bullet's lead body is partially or fully covered by a thin layer of another metal. In your case, the jacket is copper.
Unfortunately, we cannot accurately date your bullet, because it has been continuously manufactured for about 100 years, and is still being made today.