Best way to change someone's mind, in fact it's really the only way, is to provide a setting conducive to them changing their own minds. For example, tell a story or narrative from a perspective they can agree with and understand, then insert into your narrative the important points you want to get across, again in a way they understand. You can't hard sell it, but you may be able to soft sell it. Even better and more powerful is through touch and action. Get them to go shooting with you, first with something small they can agree with shouldn't be banned. Then when they enjoy it, and they will, slowly move up to the M4 --they'll enjoy that too and then you've got a convert.
Telling them they are wrong because they are literally taking Hitler's words and making them action just doesn't do it for some reason. Just has to do with humans and them not wanting to be told they are wrong. Even in academia, even in physics and rarely, but sometimes, math, you'll find professors and experts that will hold up a wrong idea all the way to their death beds. And they can do it alone, against the whole community.
When they have like minded cohorts, it's even harder, so that's what we're up against. No argument will work, only craft and action.
For instance, I wrote Obama asking him to run when I started college. Based on a speech I saw him give at Dem. convention. This was long before there was any word he'd run, it hadn't been mentioned. I probably still have the email somewhere if it was in or after 2005. That's a strong starting point when trying to get a convert, something they can agree with and identify with. Obama ended up fucking me at every turn, sometimes succeeding, sometimes not, but always persistent. I was forced to vote for Trump, and they like hearing that more than if I chose to do so. A trip to the range and short lesson on what's, why's, who's and how's and they got it. Maybe show 'em your storage if it's strong or high speed, like a jewelry vault. If that doesn't win 'em, nothing will, move on.
See what I'm getting at?
If online, you obviously can't take 'em to range, and you have to be craftier at the narrative and once they "get it" implore them to seek out a good range to try rentals before making their own purchase. Assume that's the goal at that point, always one step ahead.
