hmm... i would think that these types of AP rounds were "exotic" and generally not standard issue, which would be limited to several weapon types (ie MP5 or Uzi variants only). I *think* since im no weapon guru or gun-buff or bullet-scientist, the rounds would not fragment or expand unlike JHP and act more like the 4.7 type rounds (more hits to take down, but penetrates armour).
would be interesting to see a revival of the MP5 with AP rounds, but like any other weapon, all new weapons have a frenzy of being used then people go back to their favored weapon. So i think it would be best to wait a bit until the "testing new guns" craze has died down before seriously getting down to it.