Cleaning no4 mk2 Enfiled metalwork

I need to clean up my metal work as its a bit grotty. What would be the best way to clean off crud etc with minimal or no damage to the finish?

If you do a complete strip and clean, you could use varsol or paint thinner and fine steel wool to remove hard deposits or a nylon scrub brush. Paint brushes and tooth brushes were also a favorite for in the bath and they take off dust from dry firearms too. You can apply oil after with them...