Let's discard for now the legal and practical consideration of making RSA "gun-free". In the scenario you sketch above, criminals will still be acquiring guns illegally and the SAPS still inept. How does it make us safer? Should we not also look into policies dealing with social breakdown, socio-economic factors, domestic violence, law & order policies, policing and policies related to specific problems like gang culture. In most of these instance the means of "violence" seem less significant then trying to prevent the enabling, cultural and institutional factors behind the violence in the first place? 

For instance looking at per capita ownership rates we are not that high; and countries with lower per capita violent crime rates than RSA have much higher ownership rates...It cannot be as simply as - "guns".