Frangible Designation?

[KellyTTE]

I searched and I've looked over and I can't find a bit of info that I need. Does anyone have the mil designation for the ATK/Federal Cartridge 5.56 frangible? Its a blunt nose brown(ish) tip round.

I need to know what its "M" title is, you know, like M193 or M855, etc. Thanks guys.

[markm]

M556NT1 or XM556NT1

Not toxic.

[KellyTTE]

Thank you!