Force is not and should not be a legal problem. I have used "force" in that sense daily for a very long time - firing pistol, rifle, or usually both every day that I am not on vacation. Assuming these are serious shooters, intent to do harm would have irrefutable evidence: dead bodies. In the absence of such evidence, we can conclude that there was no intent to harm others and no crime.
As for an NRA card, I have one too, as do millions of law-abiding citizens. The people I worry about are the non-NRA members, especially thugs like Barack Hussein and his minions.
That many rounds are fired on a good weekend in Chicago.