What I think this guy did was set a very large reactive target on the ground, shoot it with his rifle, and then get surprised when all the loose rock and dirt around his reactive target turned into shrapnel.
Regardless of what preceded that chunk of rock coming at the shooter there are some important lessons here.
- Start small and work up. Whether that is starting with a .41o shotgun and working your way up to a 12G or a small reactive target and working your way up to bigger booms.
- Think about what your doing. Am I putting a small explosive device on the ground where there is a ton of loose rocks, shale, or broken glass. Yeah, because that could turn out bad.