I don't really think there is any practical short or mid-term solution to this. If you find a compromise, people will just buy a stock of guns and ammo, hide their automatic guns in the basement or whatever and the situation won't change. Most people who now can't buy guns wouldn't have bought guns in the first place and everyone else can get it via a private trade.

The only way to really work on this on the long term is to reduce the reasons why people have guns.

• Invest in public Education (Reduces crime rate and reduces gun culture)
• Invest in Police (Better training, better salaries, less police violence)
• Reduce Social Injustice (Resulting in a reduced crime rate)