[CedarDave]

This shooter in self defense was not charged with a crime. In the absence of criminal behavior, is it nonetheless NM's practice to confiscate the shooter's weapon "pending investigation"?

I don't know the answer to that. I'll pass the question on to a NM Freeper who has lots more gun/hobby shooting experience than me.

[Tijeras_Slim]

I am not aware of a case where a good self defense shoot resulted in the confiscation or retention of the shooter’s firearm unless there were circumstances under which it was regarded as evidence or some sort. We’re pretty gun friendly here.