The only poofs I've ever seen were with Rock River NM rifles shooting unknown tracers. Normally tracers aren't allowed at the range due to the fire hazard, but it had rained the last few days and everything was quite soggy and the guys firing were competent to hit the 200 yard berm, so the safety officers allowed it. There were probably one in ten poofs on whatever tracer one was shooting, none with the other shooter.
More interesting was how far they ricocheted off the berm and into the woods.
Phillip McGregor (OFC)
"I am neither a fire arms nor a ballistics expert, but I was a combat infantry officer in the Great War, and I absolutely know that the bullet from an infantry rifle has to be able to shoot through things." General Douglas MacArthur