I didn't know what category I should post this so here we are.
https://www.reddit.com/r/interesting/comments/1dbvj0f/arrows_vs_riot_shields/?ut...the link is a video of different arrow points and their penetration on a shield.
the crown head wadcutter @0:38 performs better than the rest sailing through the shield. I have seen something similar on joergsprave's channel where he was shooting plywood with sharpenned points and a wadcutter point.
It would be interesting to see such type in an arrows vs armor video. or sling bullets vs armor
the physics behind it is that while a point has less surface than a circle, it needs to spend more energy in longer time to rip through metal until it opens a hole the diameter of the shaft. In contrast if the wadcutter circle makes a square on contact the duration of impact decreases and the force increases for a given momentum, the hole opened is the diameter of the shaft or bigger so it sails through.
F=dP/dt
another thing that happens but I don't know how important it is, is that when the armor is slanted the reaction force on the pointy arrow has a better moment arm and will turn it away from the armor deflecting it. while the reaction force on the wadcutter has a smaller moment arm and wont deflect as easily.
while terminal ballistics seem promising the external ballistics aren't very good, the shape has one of the worst drag coefficients.
I think penetrating steel using a wadcutter sling bullet is worth considering