Got my "early AR" project goin' on here; I scored a set of early plastic stocks on ebay (the CORRECT ones, without the cleaning kit door); scrubbed 'em down real good with hot, soapy water, but they still have a surface patina on them, and I want to get back to a deep black. What is the process here? Should I do a light sanding, and if so, with what? Steel wool, sandpaper, brasso, etc.? He'p!

Hate to tell you this but there is really no way
to return the plastic to its original finish.
Best you can do is lightly sand then glass bead.
Depending on depth of scratches, you might try
320 paper, then 600 just to even the surface.
Then pressure blast with glass beads(instead
of sand).Many grades of glass beads are available(abrasives companies/yellow pages).
I use #8, then #12 if the stock needs to look
very smooth. But, neither will give the look
of shiny plastic.But I prefer the matte finish
anyway.You might try FN-Fal.com & search under
stock refinishing as those guys have to go thru
hell to refinish some of the foreign mil-surp
that comes in.Good luck
Oh Yeah, be sure and use a flat backer for the paper or you will just dish-out the bad areas
in to 'terrible'.

Storm- I'd try some Castrol "Super Clean" first, then use their tire dressing.. Wipe it off after a couple minutes..

I use these products to restore the clear plastic windows on convertible tops..With a stock? Hell, douche it on, let it sit, wash it off..Then the tire dope, let it sit, wipe the excess off..

If that fails, THEN go to the sanding...

Meplat-

This might sound silly but try lighter fluid and a rag/towel.

Mine had some type of duct tape on it and I was using lighter fluid to remove it. Tape came off and the area it cleaned was new looking. Did the rest of the stock and it came out really good.

I also build plastic models; I looked trough my supplies and found some "plastic polishing compound" that should provide the final shiny finish...still, I'd like to minimize the small to medium scratches first...I will keep updates on how the work goes, in case anyone out there is interested...

If you want the shiny look, you can use brasso and a piexce of short pile carpet.  You can use some fine grit (320+)paper first to get the deeper scratches out. Soak the carpet and rub the stock over it back and forth in one direction.  It takes a while, but it will get the scratches out.

Midway silicon gun rag is what I use to shine up my early M16 stocks.