[Iowa] Is it legal to fire a warning shot at a car driving too slowly on a one-lane highway? • /r/legaladvice

The speed limit on this highway is 55mph, and there are often people who go 40mph or even slower, causing huge lines of traffic behind them. The worst thing about that road is that it is one lane for about 30 miles, and there is constant traffic on the other side. It's not possible to pass someone who doesn't follow the law. I'm wondering if it is okay to use a legally registered firearm to fire a warning shot (not aimed at any person or their car) to get someone's attention who is driving way too slowly. Worst case scenario, they will pull over to call the police and let everyone pass.