RR, Here you go. Go to the sporting good store and get yourself a threaded post with a nut on it. They make them. Maybe $3.99.
Pull the barrel/action off the gun. The Ruger stock is hollow on the underside so the nut can be screwed on and have plenty of clearance below the barrel.
Put a bit of lock tite on the threads before you tighten it down. I drilled mine approximately 2" back from factory D ring swivel. Maybe about 1/2" in front of the foremost screw that is embedded in the stock.
Here is a picture, that will be easier. It is a bit hard to see cause the bipod is on and I aint taking my gun apart for you...
See if this helps. R.
