Wood moves all the time due to seasonal changes in huymidity,some more than others. The reasaon a lot of the older gunstocks are fairly stable is that thay were air dried for many years and have gone through the seasonal changes.
Todays wood is live one day and in a few weeks is used for gunstocks and furniture. Kiln dried wood is good for the wood merchant who is selling it, but not for you and I.

David