It’s been a while since I really looked into it, but there seem to be some open questions that could get him on the same standard:
What’s up with his claim that he didn’t even pull the trigger, which seems to have been misleading?
Could he have pointed the gun in a slightly different direction?
Was the shot they wanted so artistically necessary that it had to be done with practical effects?
Does an actor still maintain some residual “normal human” responsibility before pulling a trigger on a real gun pointed at an innocent person, and if so how much?
Did he, in his role as a producer on a fairly slapdash production, bear any culpability for the armorer’s actions or for hiring her in the first place? The NM statute is pretty broad, though I think he’ll more likely face civil than criminal liability here.
All in all, my gut impression is he has a very good chance at being acquitted, but it was also a fair case to bring:
Involuntary manslaughter consists of manslaughter committed in the commission of an unlawful act not amounting to felony, or in the commission of a lawful act which might produce death in an unlawful manner or without due caution and circumspection.
EDIT: @homura1650 is probably more up on what’s going on than I am.