What caused the barrel on this Mark 13 rifle to split?

By

Staff

A U.S. Air Force F-16 Fighting Falcon fighter aircraft assigned to the 18th Aggressor Squadron takes off from Eielson Air Force Base, Alaska, Oct. 6, 2014, during RED FLAG-Alaska 15-1. RF-A is a series of Pacific Air Forces commander-directed field training exercises for U.S. and partner nation forces, providing combined offensive counter-air, interdiction, close air support and large force employment training in a simulated combat environment. (U.S. Air Force photo by Tech. Sgt. Joseph Swafford Jr./Released)

My comrade Colin Kelly shot a photo of this cleanly split .300 WinMag Mark 13 barrel that went all “Acme Gun Company” during the first USASOC Sniper competition held last week at Fort Bragg. The failure occured while shooting factory loads on a flat range during an evolution with no movement that could have caused a barrel obstruction.

Take a guess in the comments.