VR holds certain amount of promise, but we are yet to see how much of its potential will be utilized in the years to come.
I don't think there's a simple solution for crimes involving firearms. A larger scale, multidimensional and preventive approach is probably the only effective long-term choice. Psychological problems, illegal firearms and suicides are certain factors that show up often in gun related deaths and they are factors that can't be ignored.
Switzerland for example has one of the highest gun counts per capita. You can bring your rifle into a cafe there without anyone minding and still it's 1 in 200000 chance that you will be a victim of gun violence according to up do date statistics.