outside neck turning ?

[Catfish]

I must agree with what everyone else is saying. If you have a factory chamber the only thing you will do is to shorten the life of your brass as the case necks will be worked more. A good way to tell if neck turning might help you is to fire a round in you gun and then try to slide a bullet into the just fired case. If it will slide in nack turning will do you no good at all.