Identifying AR receiver forge mark......

[Mark IV]

This receiver is on one of PSA's "premium" uppers with the FN CHF barrel. There was no mark on the outer right side, as is typical. This is on the bottom of the rear lug.
I'm just curious who the manufacturer might be. Any solid info is much appreciated .

 

[NWSharpshooter]

Griffin armament.

 

[rOmiLaYu]

In for info.