[1][2] As a teenager, he moved to Buffalo, New York and joined the United States National Guard.

In the 1912 Summer Olympics, Leushner won a silver medal in the "team running deer, single shot 100 meters" competition (targets, not actual deer, were used) and two bronze medals, finishing third in the "small-bore rifle teams 25 meters", and "small-bore rifle teams 50 meters".

He was a three-time winner of the National Rifle Association of America's Members Trophy, winning the inaugural contest in 1901 and retaking the title in 1903 and 1908.

[3] As a member of the U.S. National Guard, Leushner served on the Mexican border Pancho Villa Expedition with the 74th regiment.

He was a marksmanship instructor at Camp Perry during the First World War and one year with the American Army of Occupation from 1919 to 1920.