The only NFA lower (not to be confused with NEA) I have viewed was out of spec and had a plastic fire control group. The uppers appear to be ok.
If you want an alternative plastic lower they will be available in a few weeks for $NZ99.90.
Personally I would see a $999 AR15 kit with CMMG receivers, a USA barrel and the option of installing free float handguard as a more logical investment though.
Bookmarks