Urban areas in the US have very low rates of gun ownership while rural areas, particularly in the west and south, folks are armed to the teeth, and I'm not just talking about pistols.
There is absolutely no relationship between availability of guns and murder. If that were the case, rural areas acrosss the US would be under constant siege, with running firefights in every soybean field and country gas station. There are relatively few gun owners in US cities, which is where most murders are committed. The fact is that city dwellers just aren't "gun people" and very few city folks have even a passing interest in firearms, excluding of course gang members.
Banning technology won't work, never has, never will. The lure of black market is just too strong. Our borders are far too porous, keeping out guns will work just as well as keeping out illegals and drugs. How has that worked out for us? Not too well.