Armor-piercing rounds for the FN are only sold to military and law enforcement personnel, said Mangan, and there are plenty of other pistols that use armor-piercing ammo. But the FN 5.7’s have a particularly notorious reputation. In the vault that day were about 45 recently seized FN 5.7 Herstals. “FN will say its stock ammunition ‘is not armor-piercing’ but we’ve done demos and it does pierce certain types of soft body armor,” said Mangan.  (A company spokesperson said in an email that the 5.7 model “is often mischaracterized as a new firearm which shoots armor-piercing ammunition. To be clear: armor piercing ammunition can be shot from any firearm; however such ammunition has been illegal for Commercial sale since 1986 and is only available to Law Enforcement and Military.”)

Rifle ammo shot at BA rated for pistol ammo will go through it but that doesn't make make it armor peircing ...