Oh. I totally agree that it wouldn’t be easy, or even doable...my point simply is it isnt as hard to find out who has them as some might think. Just imagine “rewards” for people “seeing something, saying something”. Just imagine how easy it is to follow social media, forums, etc., and ascertain who has them. It’s amazing the amount of information that people “share” in this method.
That information flow goes in both directions. They can compile lists to their heart’s content, but so can those opposed to them...and there are a couple orders of magnitude as many people in the latter category - which is the core of the gun-grabbers’ problem.