You'd probably be wrong. Must gun related fatalities are either self-inflicted or accidental. Murder usually occurs in a fit of rage between people who know each other, i.e. found a cheating spouse, road rage, drunk and stress, etc. You don't need a gun to kill someone, and I would wager most murder occurs through some sort of beating/strangulation.
Further, the United States is 121 on the list of intentional homicides on wikipedia[1], where as Greenland (Denmark), which arguably has tougher laws is 26 on the list. However, if you compare the list to those of the poorest nations, you'll find a much stronger correlation. violent crime is far more correlated to the wealth per person in an area than gun regulation.
Gun control is more-or-less just a politically charged topic that is used to garner votes from the public based on emotional pleas.
[1] https://en.wikipedia.org/wiki/List_of_countries_by_intention...