The proposed outline for a ban on XM855 or SS109 is a 5.56x45mm NATO cartridge and is not by the BATFE's definition of AP (armor piercing) ammunition. First, a little background.
The following is that definition:
“(i) a projectile or projectile core which may be used in a handgun and which is constructed entirely (excluding the presence of traces of other substances) from one or a combination of tungsten alloys, steel, iron, brass, bronze, beryllium,
(ii) 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.”
This law only applies to handgun ammunition., not rifle cartridges therefore cannot be banned by the same means.