McNary played college football at the United States Military Academy, and signed with the Indianapolis Colts as an undrafted free agent in 2013.

With the defensive line coach, Michael Boone, looking for athletic players to fill the positions that were open, he asked to work with McNary and converted him to nose guard.

As a senior in 2010, McNary capped off his career by returning a fumble 55 yards for a touchdown in the Black Knights’ 16–14 victory over SMU in the Bell Helicopter Armed Forces Bowl.

He was also on the preseason watch lists for the 2010 Lombardi and Nagurski awards, and was a semifinalist for the 2010 Lott IMPACT Trophy, which is presented to the nation's top defensive player.

Following his senior year, McNary was honored with the 2011 East-West Shrine Game Pat Tillman Award, given to the player who best exemplifies character, intelligence, sportsmanship, and service.