Several years ago, Congress, in it's infinite wisdom and knowledge of all things technical, passed a law banning the manufacture and sale of "armour piercing" handgun bullets and ammunition. This was promoted as putting a stop to the use of "cop killer" bullets.
The sale, ownership, and use of armor piercing rifle ammunition and bullets is usually unristricted in most states. It's use on game is psecifically prohibited by most hunting regulations.
Rifle ammunition is not restricted becasue they are powerful enough to penetrate most body armor even without the use of armor piercing bullets.
HTH
John