Citristrip is great to work with. I've been using it for quite a few years now and cleaned/stripped probably two dozen stocks with it along with an oak chest of drawers. For stocks, it's perfect, for the chest of drawers, not so much. Reason I say that is it can be a bit of a mess. I do all mine in the bathtub because it gets washed off anyway and the water is right there. It also has the advantage of getting rid of any soap scum in the shower. It comes in both liquid, which I don't like using, and a spray can which again is perfect for stocks. A spray can runs about $9 at Walmart and will do about 3 stocks. Put it in the tub, spray it all over and let it sit for 15-30 minutes and then wash it off with as hot of water as you can stand and scrub a bit with a soft vinyl brush. If stock was really bad, do a second treatment immediately while it is still wet. and if really, really bad, do a third. Sometimes I will wait on the third because after a few days the oil from the inside will reach the surface again. As bad as this stock was, I only did two treatments.
It has never harmed any markings on the wood and in fact has made many visible that I didn't even know where there. After the final wash, I'll wipe the excess water off the stock with a paper towel and then just sit is somewhere to dry. Usually the wood is completely dry in 2 hours or less. I've never had a crack or warping of the wood. I don't believe the water penetrates very deep. The wood may still look dirty after the second wash but when it dries out, you'll probably be surprised how the color evens out, etc. If it still feels greasy, that's when you need to consider a third treatment. That black stuff will start dissolving immediately, the citristrip is kind of like a foam, it lays on thick when you spray it.
The reason the chest of drawers was a pain is because you can't put that it a tub and you can't really go around spraying large wood flat surfaces with a hose. They will likely crack. But you have the same problem with any type stripper so not a huge deal. The liquid form is cheaper but then you have to mess with brushes, pans, etc. For furniture, the better way to go but for gun stocks, I'd stick with the spray can.
It does have an odor which I do not find unpleasant but it does irritate my wife. It smells like crushed orange peels.