My first trade gun was made with a Madrone( everyone thought it was cherry) stock, and wasn't finished inside the barrel channel. I had tinkered with it until at short range it shot like a rifle. The week before our local Rendezvous it rained in truly biblical proportions. I took the little trader out, and literally couldn't hit anything. When it dried out again, it shot fine. I glass bedded it with micro-bed, and never had another problem. it was built from an old 30" 20 gauge shotgun barrel that was very light weight, so the slightest amount of stock swelling moved the barrel.
Hungry Horse