Darken the A2 stock (and hide the oil stain)
Many people wonder why the standard A2 fixed stock looks more gray than black.  They also want to know if there is anything that can be done about the oil stain around the sling loop.  If you don't mind the smell of CLP there is a simple way to address both of these issues - just spray some CLP on it and wipe it down with a cloth.  If you are averse to the smell of CLP you may prefer to just live with the oil stain or perhaps you should just find a new hobby :)  Just kidding folks, well not really... 
The standard A2 fixed stocks almost always have a gray appearance and an oil stain around the sling loop.
This is nothing that a little CLP and a cloth can't handle.  You can use some other form of lube but every self-respecting gun owner should have a can of CLP on the shelf.
You will probably want to use some newspapers or some other material to protect your table as the CLP tends to spray all over the place.  Just spray a liberal amount all over the stock and work it in until there is a uniform coating all over the stock.  Wipe up the excess using a clean cloth.
Now doesn't that look much better?  And no more oil stain - or you could argue that now the entire stock is an oil stain.  Now quit fussing over yer gun and go shoot it, dagnabbit!!