Delta:
Your point about informed is something that I will always agree with no matter the topic. 

I'd argue, however, that there is indeed room for objection when the fate of one of the societies you bring up (ancient Rome), for instance, came and went before the advent of firearms. Also, if you are going to introduce institutions like prisons and call them societies, I'd say the door would be open on convents, monasteries, hippy communes - and their violent crime statistics as well.

I have a problem with arguments in which the existence of radically differing "societies" and their relative rates of firearms violence are referenced as if the people living in them are all the same and the availability of firearms is the only determining factor.