An involuntary manslaughter can also happen during lawful activities that occur recklessly, carelessly, or unreasonably. A prosecutor might prosecute a defendant for a homicide that occurred due to the defendant's careless behavior related to what would otherwise be a lawful activity.

I would say shooting at seals in the dark would qualify as reckless (which the defendant said he was doing at one point) as would shooting into a crowd. The mere act of discharging a weapon within city limits is mostly likely illegal for exactly this reason. I don't see how he is not guilty of involuntary manslaughter.