I also found this on a USMC Judge Advocate site:
WEAPON REVIEW OF JOINT SERVICE SHOTGUN SHELL
We reviewed a request for a legal review of the Federal Cartridge 12-gauge, 3-inch, number 00 buckshot (AA60), for the joint service combat shotgun. We reviewed the supporting documentation and concluded that the intended use of the AA60 is consistent with our international legal obligations, including the law of war. Although the AA60 contains plastic particles, we confirmed telephonically and through the procurement of additional documentation, that there were no issues under Protocol I, of the UN Convention on Certain Conventional Weapons. Protocol I prohibits “any weapon the primary effect of which is to injure by fragments which in the human body escape detection by X-rays.” The primary wounding effect of the AA60 is the lead buckshot, not the plastic pellets, which immediately dissipate into a confetti-like substance after the round has been fired. We forwarded the request to Navy JAG (Code 10), recommending approval.
I also found another site that listed this item as manufactured by Federal. Now all I need is an M4 to shoot it in.