That was actually my next question, as that popped into my head while thinking about it. 80% by man-hours? Material? I'm not sure how you'd have a bright line rule. I think pretty much everyone would agree that a steel ingot and a block of plastic is not a firearm and pretty much everyone would agree that a Glock doesn't cease being a firearm if the slide is removed and placed next to the frame. Where is the line drawn in the process between the two?
Anyway, I'd like to read the original search warrant before getting too fired up. At this point we don't know exactly what the issue was, if the regular kits were found to be out of compliance, if the company was shipping "special kits" that were more put together, or what. I don't trust the media to get it right, as it's a better story with the 'ghost gun' angle and narrative on one side and the "they are coming for your lowers" on the other.