Spook. The one on my HMR is stamped KS63B on the left side top flat. I know this sure doesn't sound like a Weaver # but. What it appears to be is a flat (non tapered) one piece base with the rear underside milled away for approx. 1" to clear the receiver with both mounting screws into the bbl and the front end just covering the rear sight dovetail. Muddy
