I had a double barrel hammer shotgun that was oil soaked after 120 years of use. The stock just broke at the wrist one day. I had a gunsmith in Millbrook, NY repair and glass bed the stock. After re-checkering, you can't even tell it was once in 2 pieces. The guy was pricey, but good.
Bruce at Hunters Essentials is also a good wood worker. 900 Willis Ave, Albertson, NY. 1.516.741.5243.
What kind of gun is it?