Just out curiousity I googled "Polishing a Nylon 66 Stock" and there's many results.
I've never polished a nylon 66 stock but ...
The best plastic polish I've ever used for a scratch free mirror finish is Novus #2 ... and I've tried a bunch.
Use wet or dry sandpaper to remove the scratches, in steps, as needed, with finer and finer grits ending with 1000 or 2000 grit and then polish/buff with Novus #2.
I used this method with excellent results on clear plastic winshields, headlights, hard plastics, epoxy finishes, paint and clear coat. The only time I've had any difficulties is with soft flexible plastics like ATV fenders.
