I don’t buy it personally. I read a study a few years back about just this thing happening. Guys that did it couldn’t get a fire started at all, on purpose. Only fire they managed to get started was using either tracer or other incendiaries.
Experiment: Bullets don't start blaze
This is a news article on the experiments. Original posting had setups, pictures, etc to each experiment run. Too late to try to find it tonight.