I hope your gunsmith knows something about Dicksons - sadly that one is a bodgered up mess. There's all kinds of stuff in/on the action bar that shouldn't be there.
I have no idea what the screw stuck in the back left side of the action does.
I have fixed some messed up Dicksons in my time, but this one will take some saving.
The advice Steve was given to run from it was sound.