"Are Americans as a culture more aggressive when it comes to dealing with issues? ."

I think that's clear....meaning that there are SO many sub-cultures and variable ways to cope & settle disputes that when you read news reports, you do see violence and gun incidents everyday. But *I* almost never see any such thing... and almost no one I know even own any guns.
The trouble arises when the sub-cultures (defined in many ways) that DO treat violence as 'normal' get carried away and interact with us quiet folks... as in robberies or drug deals or just settling disputes in public places.

Years ago, there was an TV interview with a kid who'd been arrested. When asked "Why guns when you have a dispute? Why not just fight,,,etc.?"

He replied... (paraphrased): "aww, man... that's a hassle, and you get dirty and they might be bigger. With a gun... *blam*,, and it's over."
He really had no clear answer about the idea that someone might seek revenge..... but that same mentality existed with some mountain folks many years ago (Hatfields & McCoys)

That was a real example of how it's treated sometimes. We (America) still are not too far from a Frontier Mentality. Many people know stories of how their grandfathers (or a couple more generations back) fought Indians or defended against bears. Guns are a direct part of their history...even beyond hunting. ... and it is MY contention that having guns and using guns, even if you have never fired one in anger, becomes a habit and a hobby and a **fascination**.

UNdoing this complex culture will likely take as long as getting into it.... but it will never happen as long as 10s of millions of ALL kinds of guns are allowed & used.