That is a Fine Looking Pre-15. If it were mine, I would Break out a Tube of Flitz and a soft towel and go to Polishing it up. The Flitz Polish will take out all the fine Micro scratch's and make that revolver look as shinny as a new Penny when you are done... Hammerdown
That is a masterpiece of a weapon! I'd rather have something personal like that, than a nib version of the same gun with no soul! I bet your Grandpa would be pleased to know it was still being shot, giving pleasure, and protecting his family.
That K-38 of your grandfather's is an heirloom, I know you'll treasure it. I'm finally getting around to posting a few photos, so here is a K-38 from 1948. I believe that was the last year S&W used the tapered barrel.