excerpt:
As explained above, in 1986, ATF held that 5.56mm projectiles in SS109 and M855 cartridges were exempt. Further, in 1992, ATF held that 30-06 M2AP cartridges were also exempt. In each case, ATF found that, “it is well documented” that the respective ammunition “has been recognized as being suitable for target shooting with rifles due to its accuracy.” Id. These cartridges were originally produced for the military and were only later adopted by civilians for sporting purposes. When assembled into a complete cartridge, the projectiles were exempt, but ATF did not exempt the projectiles before the cartridges were assembled.
Applying the sporting purposes framework set-forth above, the 5.56mm projectile that ATF exempted in 1986 does not qualify for an exemption because that projectile when loaded into SS109 and M855 cartridges may be used in a handgun other than a single-shot handgun. Specifically, 5.56mm projectiles loaded into the SS109 and M855 cartridges are commonly used in both “AR-type” rifles and “AR-type” handguns. The AR platform is the semi-automatic version of the M16 machinegun originally designed for and used by the military. The AR-based handguns and rifles utilize the same magazines and share identical receivers. These AR-type handguns were not commercially available when the armor piercing ammunition exemption was granted in 1986. To ensure consistency, upon final implementation of the sporting purpose framework outlined above, ATF must withdraw the exemptions for 5.56 mm “green tip” ammunition, including both the SS109 and M855 cartridges.
ATF recognizes that this ammunition is widely available to the public. Because it is legally permissible to possess armor piercing ammunition under current law, withdrawing the exemption will not place individuals in criminal possession of armor piercing ammunition. However, with few exceptions, manufacturers will be unable to produce such armor piercing ammunition, importers will be unable to import such ammunition, and manufacturers and importers will be prohibited from selling or distributing the ammunition.8 ATF is specifically soliciting comments on how it can best implement withdrawal of this exemption while minimizing disruption to the ammunition and firearm industry and maximizing officer safety. Under the proposed framework, the exemption for 30-06 M2AP cartridges would continue because ATF is not aware of any multi-shot handguns available in the ordinary channels of commerce that currently accept such ammunition.
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Some ammunition that was previously exempted as “primarily intended to be used for sporting purposes,” specifically
5.56mm constituent projectiles of SS109 and M855 cartridges, will again be regulated as “armor piercing ammunition.” Except as provided by law, no person may manufacture or import such ammunition, and manufacturers or importers may not sell or deliver such ammunition. ATF will maintain the exemption for 30-06 M2AP cartridges.
http://www.atf.gov/sites/default/files/assets/Library/Notices/atf_framework_for_determining_whether_certain_projectiles_are_primarily_intended_for_sporting_purposes.pdf