ATF claiming upper AR15 upper assemblies are "barreled actions" and thus are "firearms" themselves.
https://www.thefirearmblog.com/blog...ying-50-cal-bolt-action-ar-uppers-as-firearm/
https://www.thefirearmblog.com/blog...ying-50-cal-bolt-action-ar-uppers-as-firearm/