Maybe he forgot targets one day when he went to the range and decided to use his tailgate so didn't completely waste the trip. And I'm thinking those look more like holes from a shotgun slug than a handgun, maybe I just have my perspective messed up. The holes are also distinctly different in size.
And yeah, I'm a nerd. I figure license plates don't vary much in size state to state, so I held up a .45 round next to an old plate in my garage, and the size in picture doesn't equate to a handgun. Just saying.
It is a pretty funny picture though.