Seems to me that on the face of it, if definitions and opinions and court injunctions change over time, that's "arbitrary and capricious."
It would be but that's not what happened, despite what they are still arguing on THR.
EP said: "Hey check this out, is it cool?"
ATF said: "No, from looking at this thing you made a Fire Control Pocket. Whatever else you did doesn't count, you made a gun."
EP said: "BS, tech branch don't know tech, we're going to keep selling these while our lower slaps you around."
ATF said: "ORLY? Wait one..."
Then they said:"Look aholes, it doesn't matter whether you form the FCP around another piece of plastic or not. We can see it, it's the black part that's not the white part. You FORMED THE FCP. It's RIGHT THERE. Your own whining shows how your *expletive deleted*it is different from all the other stuff we approved. We said NO the first time. Change your *expletive deleted*it and re-apply."
And that's where we are at. I hate the ATF, but their letter is clear, doesn't change, and even goes so far as to tell EP what would probably get them an approval letter. There's two other polymer 80% lowers on the market that aren't being messed with.
I HATE to side with F-troop, but in this case, they were pretty straight, and EP screwed the pooch. I wonder is EP Armory bothered to tell Ares that they had been found to be a firearm in Feb?