Interesting and fair list!
I believe there is a fundamental human right for self defense, defense of innocent people, and to a large degree defense of property. The firearm is just a tool. Unfortunately tools can be used for evil also.
People who have had their constitutional rights limited ( convicted felons, minors, people declared legally insane, etc.) can not legally own or purchase firearms or ammunition. Bad guys wishing to do bad things are usually not very concerned about breaking the law when they break it.
As far as the list is concerned, my opinion of the top 10 list of greatest firearms would be different. It depends on what my definition of the greatest is at the time.