Kensal: What you say about moisture makes sense, given the organic nature of these materials. What puzzles me is that, rarely, some apparent shrinkage can be substantial, while in other cases there has been none at all, even in apples-to-apples situations. I've owned century-old Winchester rifles whose buttplates still retain a perfect factory fit. Wouldn't shrinkage be common and occur consistently? I'm sure that in some cases the too-small plates we see are simply nonoriginal, but I've also wondered if different third-party suppliers might have led to this inconsistency, or if different storage methods or climates might be at work.
As to women (and most men), in my experience, over time, shrinkage is not the problem.
Best to you, TT
