A 12-gauge shotgun is not exactly effective at delivering a shock to a wheel nut, even with all that powder behind it. What did ensue, though, was a potentially deadly and certainly injurious shower of buckshot. Shooting a car wheel from an arm's length is a guaranteed way to create plenty of ricochet. The shot found purchase in the much softer organic material that comprises a human being, and the man sustained injuries from his feet to the middle of his abdomen. Next time, whack it with the BFH.
Thanks for the tip, James!