I believe the ATF is saying that the biscuit clearly marking the fire control pocket is enough to warrant their determination. However they also believe that the extruded pins showing where to drill the fcg holes are enough to warrant the determination. They claim that regardless of whether or not the biscuit is made first, the receiver is a firearm.

They have made their stand and they won't back down. Especially considering the ATF head has been making an ass of himself on Capitol Hill, unable to reasonably answer many of their recent questions, I don't believe they will let this go no matter what.

When I first saw EP Armory's 80% lowers I thought to myself "wow, self, this is neat but I hope they don't get in trouble for making it too easy!"

It will be interesting to watch the battle unfold ...