In May 2017 a Canadian sniper broke the world record for the longest confirmed kill shot. The soldier broke the previously held record of 2,475 meters away by over 1,000 meters. The sniper was over two miles away from his target and made the shot with a McMillan TAC-50 sniper rifle. The .50 BMG bullet took 10 seconds to reach its target and travelled faster than a commercial jet.
Learn more about .50 BMG caliber https://ammo.com/rifle/50-bmg-ammo#caliber-history at Ammo.com.