Banning guns is unrealistic.
There are so many hot weapons that it would be impossible to try to get them all. Chances are that the weapons are not going to land in the hands of conscientious citizens but with people who caused the guns to be banned in the first place. Besides, it would take a massive and expensive effort to try to get rid of them all and even then, it wouldn't happen.
Gun bans work better in European and Japanese country because they were enforced shortly after World War II. There was greater benefit to taking away weapons in those countries because it was best not to arm Soviet funded operations. Let us not forget The Troubles in Northern Ireland, which caused thousands of deaths in such a small area. So even gun bans then have proven to be rather ineffective.
At the same time, the 2nd amendment is outdated. A militia would get mowed down in minutes. The US government is so far ahead of disorganized shack losers in Montana that if none of them could probably get a shot off without having 50 bullets in them a split second before they pull their trigger.