I look for older .22 rifles, like the Stevens Boys rifles and a specific few of the older "name brand" bolt action .22 rimfire rifles that could use some tender care. Quite often I'll find some of these riffles having black stains where the receiver or metal butt plates meet the stock wood. When stored these rifles most often were put away after oiling and then stood on their butt stocks until next needed. The oil then runs downward and eventually will find its way into the open capillaries on the end grain. The capillaries are what draw water into the tree wood when it was still alive, and it seems the tree doesn't realize that it's now a gunstock and no sap needs to be delivered to the leaves. When restoring an old stock, where you find those ugly black stains in an otherwise nice walnut stock, and you have the patience to do so, that dark oil can be drawn out of the with a little time..............and that old hairdryer when used during the "big hair" days. One method I use involves a powder called "whiting" that I get from Brownells. I'll mix this powder with mineral spirits into a fairly wet slurry and then brush it into all of the black oil soaked end grain. Then point the hairdryer onto the slurry and watch as it turns brown from drawing the oil out of the end grain. It's possible to get quite a bit of that soaked in oil removed, but in many severe cases, some of the wood will still have a grayish color involve that wood stain will cover before finishing. So, how do you know if you have ANY oil in the end grain capillaries of your stock? Just put your old hairdryer to work and put it on medium heat and point it at the end grain. If you see oil bubble out, you do.