Since it would have been the very basic maybe jst boiled linseed oil and not stain or perhaps the gun would have no stock finish? Would the barrel and lock have been browned or left bright?
mlbrant,
I think you will have sensed by now that the guys on here think a TG is pretty essential hardware.
Surviving examples of simple rifles (such as the Appalachian poorboys) generally seem to have had some colorant added to the wood (either Aqua Fortis or at least something simple, such as walnut hull stain, or turpentine and tar), and most if not all seem to have been treated at least once sometime along with way some kind of oil. (To neglect this runs a risk of the stock being damaged and warped by water.)
As for the metal, even a simple gun left in the white will rust, and will rust quickly if used in bad weather and not cleaned carefully and oiled carefully after each use. That is to say that even guns left in the white will eventually take on a mottled mixture of brown and grey over time.
The main issue then about finish (and what Coryjoe is referring to, I believe) is not just in whether or not a stain is applied or whether or not an oil is applied, but rather in how
finely, that is how
smoothly the surfaces are prepared. A simple “poorboy” type gun (barn gun, etc) such as you have in mind would have probably had scraper marks left on the wood, for example. The barrel would likely have been draw filed (which was often part of the manufacturing process) , but not polished bright. Likely to have a few hammer marks left in it from forging (assuming an old hand-forged barrel here).
The lock would likely have been installed “as is,” with the finish that came on it as it was delivered (from England or Germany, depending on region being represented), without being polished. What would that mean? Open for interpretation. For example, a cheap lock (which is what you would expect on such a piece) might be darkened by having been case hardened (so as to turn the iron to steel), but would not necessarily show much if any polish (beyond what might be necessary for fitting the hardened pieces back together). (Others on here may have a better informed opinion on this particular element than I do.)
Overall, it would be simple. Very simple. But not necessarily crude. You need to keep in mind that even the simple firearms were usually built by smiths. They knew their job. They chose what they would do and what they wouldn’t, depending on what the customer was prepared to pay. But they did not generally neglect function. For example, on even the simplest mountain rifles (Appalachian poor boys) the barrel was usually rifled to precision and the muzzles were expertly finished, and the sights were well designed. And they sometimes had precisely made set triggers, for example, even if they had no butt plate, no muzzle cap, and only a simple bent-strap trigger guard. The goal was FUNCTION. So they would forgo details of finish, but not function.
You can go with a simple finish. But you do not want to forgo function. (Thus all this concern about the Trigger Guard!) If you take a careful look at the Hershel House poorboy in the link I posted above, you will see what I mean. Simple, unrefined finish, but good attention to function.
I hope this helps give answer to your original question.
Whet