always break it down and dry and oil

Did a little Google search and found this. Corresponds with what I have seen.

"Referencing pages 245-7 The Browning Superposed...

In part... the process was sold to Browning in 1965 from Morton Salt... affecting 90% of all Browning Firearms 1967-9... continued until 1972 in much smaller numbers... in 1972 they eventually burned the remaining blanks... as a general rule higher grades more likely to be affected than grade 1s... butts more than forearms... recommended to check all firearms from 1966-72... originally discovered on the T-Bolt rifles, eventually found on all including Mausers and Hi-Power pistols... warranted to original owners with registered warranty cards - secondary owners directed to other repair sources.

Told to Schwing from interviews with Harm Williams and John Val Browning - 1993."

I got this from TrapShooters.com. I will say I have seen the rust problem on a lot of guns from just about all makers. My advise is take the wood off, dry it off as best you can and seal that end grain. It's a simple job with the exception of some side by side guns with side plates. L. C. Smith's being an example.