Let me start off by saying this is not a slam against the vendor DennysGuns. Denny is a great guy and gives great service. Shipping was fast, and in this case FREE.
I ordered one of the bolt on, rifle length, underforearm rails. It is apparently not to spec.
The rail appears to be out of spec. None of my rail mounted accessories will fit the rail. The rail appears to be to small from side to side. Accessories will go on the rail, but will not remain in place because they are so loose.
I have tried mounting the following:
KAC Forward Vertical Grip
ARMS 22M68 Aimpoint Mount
GG&G M3 Flashlight adaptor
Weaver brand 1" scope ring
The KAC forward grip will slide on the rail, and will tighten up, but only because of the design. The screw that holds the grip in place pushes against the rail and holds tight. However the grip, if at all loose, will move from side-to-side.
The ARMS 22M68 mount will not lock down. There is a great deal of side-to-side play, and it also moves front to back.
The same symptom applies to the GG&G mount. At its tightest point the mount will hold the rail but rattles when you move the rifle and still will slide front to back with the movement of the rifle.
The Weaver brand scope ring will hold the rail and is the only accessories that hold tight enough to not move.
Clearly the rail is well made, but appears to be made for civilian Weaver accessories and not for the military standard rail accessories that I'm trying to mount.
So you may want to think before you order one.
Denny's response was super.
"We do not make the rail but the company that we get them from did have some issues with their mfg. Just return the rail and I will refund you, including return shipping and sorry for your troubles."
Thanks Denny. I appreciate the GREAT service.