Obama needs a faux excuse to ban.
About all centerfire rifle cartridges are "armor piercing" BUT the M855 is not made to be an AP rifle round. Here's the federal law.
"Armor-piercing ammunition, sometimes referred to as metal-piercing ammunition, is ammunition that is designed primarily to penetrate metal or armor, including body armor commonly worn by police officers. Under federal law, armor-piercing ammunition is defined as any projectile or projectile core that may be used in a handgun and that is constructed entirely from one or a combination of tungsten alloys, steel, iron, brass, bronze, beryllium copper, or depleted uranium.15 In addition, armor-piercing ammunition is defined as a full jacketed projectile “larger than .22 caliber designed and intended for use in a handgun and whose jacket has a weight of more than 25 percent of the total weight of the projectile.” Id. The Attorney General is required to furnish information to each licensed dealer defining which projectiles are considered armor-piercing ammunition as defined in 18 U.S.C. § 921(a)(17)(B).16
The federal definition of armor-piercing ammunition, which is based on its content and weight, rather than on the ammunition’s actual performance against body armor, has been criticized because it fails to halt the manufacture and sale of all types of ammunition that can penetrate body armor.
The existing ban on armor-piercing ammunition can be made more effective by adopting performance standards that require ammunition to be tested for its ability to penetrate bullet-resistant vests and body armor, as opposed to the existing standard based on the bullet’s content."
The BATF is not being truthful as the M855 is categorized as a ball cartridge made up of mostly lead.
The purpose of the BATF is to relieve you of your firearms.
It is what they do, however they can.
The wordsmithing is only sleight of mind, while they nibble at the cheese.