Re: Not good
The real data shows, very clearly, either a zero impact or a rise in violent crime in a given area when strict gun control measures are put in place. In the UK, for instance, violent crime rose for 10 years straight before plateauing when they took your guns away.
But out of context. When do you think gun control was introduced into the UK? I suspect you are thinking of the changes enacted after the Dunblane shootings, however guns have been controlled here for a lot longer than that.
Context: The UK has a tiny number of violent crimes compared to the US (even allowing for 5x the population) a small change in a small number is not very much, any change to the quantity in the US is far more significant.
To argue that gun control has no effect of gun related crime is absurd.
The best solution in the US where guns are far too entrenched probably is to restrict access to ammunition, bullets not used in gun clubs or ranges should cost about $100 each, for personal defence $100 is a bargain but for other uses the cost is restrictive. Legitimate hunters could buy replacement ammo cheaper by turning in the empty shells. All guns should be kept in a locked gun safe, even the NRA agree with that one, or at least used to.