I just bought some stock blanks. They're not even blanks yet; they're paid for, but the lumber mill won't have the logs until the end of October.
This is my first time working with wood stocks, so I've been reading up on proper drying of the lumber. What I've found on the woodworking forums and various Department of Agriculture and forestry sites tells me the wood is correctly dried when its internal water content matches *ambient* humidity. With the stock and environment in equilibrium, everything is fine. When they're mismatched, the wood can warp. Mostly they're talking about things like long, skinny table legs on expensive furniture, but a table leg is close enough to a gun stock for me.
So, if you have the humidity in your safe at 5%, that's great for the metal parts no matter where you live. And for the wood parts, assuming you live in New Mexico, Arizona, or Colorado. But taking the gun out of the safe and exposing it to 80% or higher humidity is about the worst thing you could do to the wood. So when your rifle that you zeroed on a 40% dry summer day patterns like a shotgun on a foggy 90% fall day... maybe there's a connection there/