Would you happen to have a copy of that letter or a link to reference?Atf did put out a letter back in the day that feed lips do not make a semi bolt a machine gun bolt. Lower feed lips were ok’d by the atf as just having the lip doesn’t constitute a mg part and would take many other alterations to make the gun FA. That being said, yes this WOULD work as a FA closed bolt if you had a registered receiver gun or a registered sear gun, or a post sample you could run this as a closed bolt setup
There is a reference number here in this letter from d and d salesWould you happen to have a copy of that letter or a link to reference?