What kind of stock finish would have been historically used on maple rifles in the 1700s colonies?
Iron nitrate stain was used a lot historically, made from nitric acid alone or nitric acid combined with dissolved iron in water, though it was not universal. As far as topcoats, finishes varied but a linseed oil based varnish was common, and it would not have been equivalent to today's hardware store linseed oil, which is not recommended for use now either.