I have built several Mono-Pod devices which turn the BAR into a gun with a tri-pod mounted weapon. The mono-pod fits into the hole on the sling swivel on the bottom of the butt stock. The device was copied from the one pictured in the BAR book - Rock and a Hard Place. The original experimental mono-pods were made from steel. I made mine from brass so they can't be mistaken as originals. Asking $300 for the one I have left Bill