Hi Harry:
I use Gun Sav'R Hunter Satin from Brownells....part number 641-20...manufactured by Chem-Pak Inc., Martinsburg, WV 25401....
After application and 48 hour curing, I hand polish with Carnuba wax to the desired gloss or satin finish depending on the gun and customer requirements.
All the stocks are first, of course, soaked in an air tight acetone bath and then an air tight lacquer thinner bath...for over 48 hours combined....repaired as necessary, steel pinned, epoxied at the head etc., then stained the appropriate factory color. Lot's of steel wooling, detailing etc., then the final finish of Hunter Satin is applied.
If you want to be completely period correct for "field" grade guns, use varnish and hand polish to the desired finish. Varnish will however, yellow in time and is vulnerable to gun cleaners etc....Hunter Satin looks like varnish if it is applied properly but is much more durable. Comes with instructions in a liquid or spray. You can fill all the grain or leave some open as was original, your choice by the number of coats you apply.
Best Regards,