A few thoughts on gun control for places like the US - just my opinion. They are not going to beat the gun lobby by passing draconian anti gun ownership laws. Instead it is done gradually - my idea is - First point - everyone wishing to own a gun can continue to do so (except convicted criminals etc, 5th amendment or whatever) but must go through a formal application rigmarole and register their details and the details of every gun they own, so a central computerised database can be set up. Anyone caught in posession of an unregistered gun, or a gun with serial number removed, is dealt with harshly - custodial sentence. The gun would be confiscated and destroyed.
Second point - to own a gun you need a licence which you must renew periodically, at a cost, together with certificate from your GP, at another cost (as in UK). Each gun requires a separate certificate, at a cost, with semi-automatic military hardware etc costing much much more for the licence.
Third point - licences gradually increase in cost so that it becomes financially difficult to legally hold multiple weapons, especially mass killing ones. Eventually just owning one might not be worth bothering with.
So basically you try to minimise the legally owned guns, whilst making illegally owned ones easy to identify. I don't know if it would have any effect but could be worth trying.
I emailed President Obama with these ideas - he didn't reply.