I figured it's going to be a chore to get all the fouling out. I don't have the option right now to shoot so I'm going to have to resort to letting the solvent work and old fashioned elbow grease.
If you use a copper cleaner that has ammonia in it be sure you get all that out within an hour as it will eat your barrel. I agree a thorough cleaning will restore the accuracy well within hunting spec.
Once you clean it, try some heavier bullets too. I had a rifle go south and couldn't figure it out until I bough some 180 grain bullets and it shot them perfect.