Listening to the prosecution cross Rittenhouse - talking about racking the gun and attempting to talk about hollow point bullets exploding and not going through a target vs FMJs that are designed to go through the 1st target into others. It was sad that the judge had to stop him and explain expand / explode and basically just shut his line of questioning down and say screw it, time for lunch.
OMG - FMJs are designed to remain intact - period. They are used in war to minimize the amount of parts and possibly sharp fragments that medics have to remove and to improve survivability of being shot. Hollow points are banned under the 1899 Hague convention in war for this very reason.
HP expand/mushroom (not explode) causing a much larger wound cavity which in hunting is more humane since your target usually drops fairly quick vs your target runs off and bleeds out miles away on someone elses property.
I am sure that they are attempting to spin it with since he used a FMJ that just goes through a person and just keeps going through bunches of people - he did not care in what bystander the bullet stopped to attempt to claim he was wreckless.
Chances are his buddy purchased FMJs for target practice because you can get them cheaper and usually in higher quantities then purchasing hunting rounds/HP.