Wonko,
No ! my Krieghoffs are Poly factory finish , a bugger to scrape off , and the Krieghoffs are not 'proper' guns that deserve TLC.
Being retired now I rarely do a stock finish or repair , but I must add that in my working career I do know that H&H, Purdey and many of the Italian manufacturers did use Tru -Oil because it was fast , cheap , and hard wearing . BUT it is NOT a true oil finish , call it what you like ,but it is a varnish.
To add I have found that my oil recipe posted on here does dry faster if you use Napthalene or Lighter fuel as a solvent / drier.
My oil finish has and is still being used by many ' BEST' English gunmakers .