An AR-15 has one real use for civilian gun owners. It’s a recreational weapon that most gun owners enjoy shooting at a range or open space. It is not a hunting weapon and isn’t very practical as a home defense weapon. Eliminating it wouldn’t really be that big a deal. It’s recreational. As you alluded, the problem is the NRA continues to hold the line with the slippery slope argument of first the government will come for the semi-automatics and then they will come for the rest of the guns.
It doesn’t have to be this way. If we can find a way to draw the line and separate these guns from the rest then we have a chance to eliminate them. That’s why I think it’s so important to delineate between controls to stop mass shootings and traditional gun control measures aimed at handguns.