No one knows exactly how firearm technology found its way to the West from China, but by the 14th century, guns were so well-known throughout Europe that we'd be astounded if horse-by shootings weren't a daily fear.
Alphonso de Spina
Look at his face: the demon on the left is just realizing he brought a crowbar to a gun fight.
So, why don't portraits of old-timey knights look like N.W.A. album covers? Well, it turns out that the use of gunpowder in battle just wasn't very efficient, which is why guns coexisted with other weapons in battle for hundreds of years, rather than overtaking them. But any and all efficiencies aside, you cannot deny the badassness of a medieval skeleton wielding a bazooka.
Sadly, being conceived in the 1400s meant this image ended up as a fresco instead
of the heavy-metal album cover it was destined to be.