I just bead-blasted my A1 butt stock and grip because they were "slightly" used.  The stock looks just like the A2 in color now, but there are some "voids" that I would like to fill, (like the number 48 scribed in the back and the previous owners intitials).  Should I use BONDO in these areas and then sand?  Would I be better off just using a spray-on Primer and then sanding?  Also, has anyone painted one of these things?  Any type of paint to stay away from?

Regarding the grip, after bead-blasting, the grip has taken on a new color (kind of speckled yellow and black), looks cool, but I want it black.  If I spray paint it, will the paint eventually come off from swear?

I also am refinishing an old stock set, but its the earlier type with rubber buttplate. I tried using a polishing compound, but with the early type of fiberglass used, once the surface finish has been ground down it is gone forever...I settled on multiple applications of a urethane-based tire/vinyl dressing, and have gotten very good results: the stocks now are a glossy deep black, very much like the origional condition...
DO NOT use Bondo for the pits and scratches! This cheap crap will not adhere to the stock properly...instead, use Epoxy Putty, a two-substance material like thick clay, which comes in the form of two bars which are kneaded together in equal amounts; a common brand is called "AB Putty" and can be found at any hardware or pool supply store...it can be shaped with a damp cloth when wet; if the stock surface is roughened it will adhere very well, and when dry is as hard as steel...
Probably the only option for getting the Black color after bead-blasting is to paint...If I were you I would call up a local fiberglass shop and ask for a recomendation...good luck!