To each his own, but why bury any nice grain ( even Teak is interesting to look at) with dark stains or paints??
I wish I had a hundred dollar bill for every stock I have refinished for friends, where I removed whatever finish/stain/paint was on the stock only to find some very nice grain. When I did a few " tricks" to bring out the grain, and then finish the stock appropriately, the owners always liked the " new " stock better than what they gave me. Most didn';t recognize their own gun. One man insisted on checking the serial number on the gun with his records! All have reported the Oohs and Ahhs from family, friends, and hunting companions on their " new " gun.
If you really want dark wood, I vote with those who suggest you just paint the stock black, and be done with it.
On original guns, the dark stocks are often( altho not always) black walnut to begin with, and then have seen dozens of coats of linseed oil rubbed into them over the years. UV light darkens these finished, and dust, dirt, and grime, contribute to darkening the finishes so the stocks look black in the museums where we now see them.
Clean those finishes with " Homer Formby's" cleaners, for example, and you see the wood grain that has been there all the time. Most people are surprised at how dark varnish and oil finishes will get over time from just being exposed to light. Lacquer is no better.
There are some synthetic finishes now that have UV blockers that don't darken with age and exposure, but they are not appropriate for use on these replica firearms. They are popular with wooden boat builders, and owners.
Best wishes to you on this project. I just don't like Black stocks! :hatsoff: