I was playing swap the guards just now and noticed the hand guard on a PSA 16CHF upper I've had for a couple years looks like it has the newer style M-Lok guard.
Reason I ask is I swapped that out with a older MOE guard in olive drab I had laying around to use on a new upper coming on for the time being.
The one I swapped off my PSA has a "M" on the right hand side, same as one I used for a Colt 6920 OEM I bought last fall.
Just wondering. The new upper (BCM 14.5 pinned Socom) is likely to become my new SHTF rifle and I want to make sure I use the right grip and mounting hardware for "goodies" (my current SHTF is a BCM 16" Socom I know has the older Magpul guard on it)