Ya, not a good idea! What most likely happened is the buckshot ricocheted off the wheel and peppered him, which will happen with projectiles that consist of certain material formation and velocities... I've been smacked with ricocheting birdshot fired from a 12 gauge, as well as a couple near misses with a ricocheting .22 LR round... Yet a .223 FMJ round has virtually no risk of ricocheting in any of the 'tests' that I've administered, as it's a fairly high velocity round, and seems to fragment upon impact...
Oh well, sometimes gun safety needs to be learned the hard way!