I managed to get my hands on two armor piercing projectiles for the French 47mm Mle 1937 antitank gun. Both are missing the ballistic caps. This was obviously an issue with this ammunition in service as you can see in the attached photo of a captured gun; several of the rounds clearly do not have their caps. I also have an image from a Russian manual showing this ammunition with and without the cap. I cannot tell from my examples (too much corrosion damage) how the cap was attached. Was it simply a poor design for a press fit; there is a little area for the cap to attach? Was it threaded on? The cap in the photos is a reproduction. It is my understanding the caps were made of magnesium. I also compared the antitank gun projectiles to the tank gun (Mle 1935) armor piercing projectiles in one photo. The antitank gun projectiles have wider driving bands that are spaced farther apart.