Either you know something about the future 18 months that we don't (civil war, race war?) or you don't know what you are talking about. Total gun related death is typically about 12,000 per year, so 18,000 per year and a half, while total military casualties in the Vietnam war were about 58,000. And once again, ⅔ of those are suicides.
I don't know about Civil War, but Mr Google when asked "Gun deaths America" says
"According to the Centers for Disease Control and Prevention, in 2013, firearms were used in 73,505 nonfatal injuries (23.23 per 100,000 U.S. citizens) and 11,208 deaths by homicide (3.5 per 100,000), 21,175 by suicide with a firearm, 505 deaths due to accidental discharge of a firearm, and 281 deaths due to firearms-"
So about 33,000 deaths and 73,500 non fatal injuries in a year. 18mths is pretty close to Vietnam.
Your other comment about
"Europe has more mass shootings than the U.S."
We call Europe a continent. It actually has a whole lot countries with a population over twice the USA. A lot of those countries have a lot of civil issues especially in the Eastern Bloc.
If still in denial try this from the NY Timeshttp://www.nytimes.com/2016/06/14/upshot/compare-these-gun-death-rates-the-us-is-in-a-different-world.html?_r=0