I have absolutely no idea what the Howards "Restor-A-Finish" consistes of but a Home Brew mix which works very similar & was published by a British restorer of early Sewing Machines which he called "Fenman's Magic Elixer' consists of equal parts of a solvent (turpentine/mineral spirits etc) Vinegar (Fenman preferrred Malt Vinegar) & Linseed oil (Fenman liked Raw). For severely dirty applications a half part of de-natured alcohol can be added. I have not tried this mix on a gunstock but it does work wonders for its intended use. I used Turp, Malt Vinegar & BLO. Most of the early sewing machine cabinets were finished with either oil or shellac & it works great on either.
