What would be the best way to attach a rail to the forearm of a Choate Dragunov synthetic stock for mounting a foregrip?  Would it be as simple as drilling the stock and attaching the rail with screws, with liberal amounts of Loctite/JB Weld/other epoxy thrown in for strength?  I was thinking that if there's enough material I could carve out a groove for the rail to sit in for extra stability before being permanently attached.  I'm interested in long-term use and worried the rail will loosen over time if not installed properly.  Thanks for any advice.

my advice would be not to fork up a good stock with a foregrip.  You realize it will not add any functionality and will look silly don't you?

Depends on the construction of the stock.  

If it is solid, determine where you want the rail.  Drill the holes in the approriate spots according to the mounting holes on the rail.  Screw in with self tapping screws (make sure they aren't too long).  Might want to apply a little 5 minute epoxy to the holes and under the rail for more strength.

If the stock has a skeleton structure inside, determine where you will have to drill, fill the approriate spaces with epoxy, let it fully harden, then install as above.

Shaving out a little material for better surface to surface contact would probably help too.

Should be rock solid...