Funny how most folks think that "dark roast" or "french roast" coffee has more caffeine. Actually, the darker roast coffee's have less caffeine, with one caveat.....that they are composed of 100% Arabica bean coffee.
The companies that boast about their coffee products as having very high caffeine content boost the caffeine in their coffee blends with Robusta coffee beans....which contain approx. twice as much caffeine as typical Arabica beans. Companies like "Death Wish" and their "Valhalla" blend actually boast about the roast....the caffeine content of their coffees. I'm not sure if Black Rifle adds any Robusta to their blends or not, but they are tasty, and pricey.