The traditional adhesive for fixing makers labels into Brit vintage gun cases is and was "Rabbit skin glue". A number of good reasons why, it does not stain the paper, easily reversible for changing labels, easily removed from the case internal Baize without staining, has a grip second to none can last a hundred plus years. A lot of modern adhesives such as pva are not reversible though a good quality wall paper paste works well and of course can be reversed.

The only lessons in my life I truly did learn from where the ones I paid for!