How would you know that? Is there a counter on the NRA web? Like the debt counter?
It is extremely rare, and well reported, when a member of the NRA kills somebody through illegal action. If there was one that did, he may be a cop or something defending himself, but the likelihood of one of their members killing somebody other than in self-defense or the line of duty is slim. You should remember that their membership is less than 1% of the nation (maybe slightly more than 1%, but I think it is less).
I could be wrong, but I doubt it. Hence doubtless... zero.