Maybe that could have been tried a hundred million guns in possession ago.I believe children are allowed to own guns in most states? I guess it's very hard to restrict access to guns in America because the right to use them is enshrined in the Constitution. Also, it's probably quite a circular thing now: everyone has them, so everyone needs them to protect from everyone who has them.
In the US, even the suggestion that there may be more restrictions coming causes record gun sales and stockpiling.
I honestly think if politicians made it clear that they weren't going to "take away 2nd amendment rights" as feared but implement sensible measures such as holding adults accountable if their kids get a hold of their guns to commit a felony, better background checks and less loopholes etc etc, they could get some needed measures passed.