In these firing experiments, two telephones provided with Blake transmitters were used for timing the bullet's flight. One was placed within a few feet of the rifle, to receive and transmit the sound of the shot. The other Blake unit was nearly two miles downrange in the shelterproof, which was located about 30 feet in front of the right edge of the target.
At the instant the sound of the discharge was heard over the telephone, a watch ticking fourth-seconds was started. At the sound of the bullet striking target or sand, it was stopped. Average time of flight for the .45-70-500-grain load was 21.2 seconds, With the more powerful .45-80-500-grain cartridge the time-of-flight was 20.8 seconds"
21 seconds. All objects fall at the rate of 32 feet/sec2. That means the guy arched this thing how high in the air to hit the target.