In the beginning an uneducated society may blame URPOs that wrestle guns away from perpetrators for then killing said perps but there will never be any video evidence (taken by the URPO themselves) to support such claims. Besides the fact that they have no motivation to kill because A, it's not in their programming and B, guns don't do them any harm.
Also I would design their outer surface to absorb rather than deflect bullets as much as possible.