I've had some minor successes over the years when confronted with people who say "No one should have a gun!/Guns are evil!" etc., by simply asking, "Why?", and letting them attempt to lay out a cohesive argument, which they are usually unable to do; their opinions generally being received rather than a position that they have come to through applying their own logic and knowledge.
Pointing out that shooting (in several forms) is an olympic sport, that it is no more militaristic than archery, and also telling people how many legally held guns are really out there - off the top of my head about a quarter of a million shotguns and at least a million air rifles - and how infrequently, both proportionately and absolutely, they are involved in any kind of misdeed has led to quite a few people changing their minds IME, at least reaching a kind of indifference rather than hostility.

As for 'military looking' guns, most of the public can't tell their arse from their elbow or a BSA Lightning from an SA80 so this kind of appeasement and self-cannibalisation is deeply unproductive IMO. Shooters of all stripes need to stick together, end of.