Re: "How do we protect our 2nd amendment & our kids at the same time? "
"I accept that guns have become more lethal"
There hasn't been a significant advancement in lethality of small arms since 1885. The first semiautomatic rifle was introduced back then, and little has changed since. One might argue that the final evolution of the modern rifle was the M1 Carbine, claimed to be the first magazine fed semi-automatic light rifle, developed in the 1930s and deployed in mass production in 1940, but the Garand was deployed in 1936, and one can certainly argue that rifle was the first modern autoloading rifle... But if you're going to say that, you have to admit that the Remington Model 8 was the first modern autoloading rifle, in 1905.
Pistols haven't changed much since the early 1900s either. The same caliber rounds are in use now as then, with a few exceptions, like 10mm, which is not significantly different than .45 or other rounds that are over a hundred years old.
"and possibly more available"
You used to be able to buy BAR 30 cal rifles and Thompson machine guns mail order from the Sears Catalog and they didn't keep records. Yes, you can 3d print the receiver for a more modern rifle (though designed in the 1950s), but the barrels and other components are just as available as they were since the 1800s. Mail order or in-person purchase.
In conclusion, I submit that neither the lethality nor availability have significantly changed for small arms since at least the first years of the 1900s and that these rifles are rarely used in crimes in the US.
There are more people.
There are more mind-altering drugs in use.
There are more mind-altering medications in use.
There are more other things in play that could impact one's mental state.
I accept that people will disagree with these conclusions, to that I say, go buy one and see what it takes. In no place in the US can you walk into a store and purchase small arms without a background check, except private sales which has always been true (and a black market will always exist).