Problem is the receiver was built in two steps, first the plug and molding the rest of the lower around it. Most 80 percent receivers are cast in one step. ATF is contending that the second molding is not a 80 percent complete receiver (the trigger/safety void is complete) thus violate the regs or spirit of the regs. If the EP process is acceptable what is to prevent someone to mold a 90 percent finished receiver (which is illegal) and fill in the trigger/safety void with wax. All the user has to do is heat the receiver and pour out the wax and drill out the pin holes. This needs to be resolved in court to determine technically if the second mold around the plug violates the 80 percent rule or is the product judged on final and not in the middle of the process. ATF does have one black eye, EP Armory cannot sell the product without ATF approval. The ATF approved the design for sale and now are having second thoughts on the approval. In the past courts have backed the ATF if the agency can show the original approval was an error in assessment by the agency.
Again, at no point is there a void in the firearm till the manufacturer puts it there.
The plug itself is not a firearm anymore than a cast is a firearm.
Anyway, here’s video of the raid.