I have recently bought a Steyr Prohunter in stainless synthetic.

I removed the stock to see if I could drill to fit a traditional lug, to take a bipod.

The inside of the stock is hollow with a deep spine that runs fore and aft with suporting ribs every 2" or so.

This prevents drilling in the centre.

Any ideas.

Cheers Rob T

If you drill from the outside in, right on center of the rib, you should be able to place your sling stud through and either break out a section of the center rib and drop a large wad of epoxy over the interior nut/stud, or put a large 1/4" fender washer on the inside to stabilize the stock and support the sling stud.
Of course, there are probably only about 400 other ways to do it also. - Sheister

Just drill the hole to mark where you want it. If it hits solid material, use a rear syle sling swivel stud with screw type threads, or use the process mentioned above.