On May 1st our indoor rifle range opened. A beautiful state-of-the-art facility with Kongsberg electric shooting system, overhead trolley system that stopped your target every 25 yards, and one lane geared for reloading and load development. The back stop was crushed tires (similar to the Barnes factory range) and half inch steel plate. There are 2 RSO's on duty and very strict rules. The only caliber not allowed is a 50 bmg however there was one shot in the lanes to make sure it could indeed handle it. The range was open for roughly a week, and somehow there was a fire in the tires. For you that have had a country bonfire and have thrown a tire on the fire, you know how hot and what a mess it makes. Needless to say, she will be closed for along time. All the sound deadening material needs to be replaced, everything wiped down, deodorized, disinfected etc. So the only round I can think of that can start tires on fire is the 50 cal tracer rounds. I'm curious to ask all of you if you've had any ideas of what happened. We are all boggled.