Hey legionair
That was my initial thought. However the second pic, and other pics in the ebay ads show a second arc, or gap, below the valve arc. Seems too far, too much space just to pin/ grub screw the new valve body in place.
Also, if the breech is the same size as the previous generation, which I have, the front of the breech ends right where the screw for the trigger frame goes. but still the pic seems like there is still a gap between the mystery bracket and the trigger frame thickness