Wood that was cured, or dried faster using salt. Great idea, and it worked great. Except...
the wood soaked up the salt, nobody paid attention, and installed them on new guns.
They paid attention later, when customers were returning expensive shotguns that looked like they sat in the ocean for a while.
Google "salt wood", you'll find more info, and I think there may be even some models and years listed somewhere too.
BTW...Midwest Gunworks doesn't list any that are salt wood.
Take a look at some of what Macon offers:
Exactly what kind of fit problem do you have with the stock on it now?