[@Doc Doctor]

While there were many misconceptions about plate armor when it went up against firearms, any knight worth their salt knew that having thick armor was merely half the story (Well... unless you had the raw physical power required to bare the weight of several ridiculously thick slabs of metal as armor like the damn greenskins). Good plate armor was designed to slope, redirect and reflect whatever came at it; It was designed to make glancing hits, arrows and bullets bounce off of it. 

Fortune's armor was good armor and it did its duty; The bullet from Donny's gun struck his elbow at an angle and was bounced off to the side without punching through the armor itself... however, the sheer force behind the impact was still more then enough to cause problems as the blunt force of it fractured the bones in Fortune's elbow, causing him to scream in pain as he clutched his wounded elbow while he spun in the void a few times.