Factory barrels and nuts ... I use a good penetrating oil applied over a few nights. They pop off easy after that even if fitted by a gorilla. I've literally done it with action wrench, nut wrench and rubber mallet whilst sitting on the floor. Hardest for me has been getting a feel for when setting the headspace, used the Go/NoGo which is easiest and then 'adjusted' how far the bolt handle will come down on the No Go, used a Goo and added cellophane to create the No Go, even a fired case and feel. Lots of ways to skin this cat, and however your chamber is set up headspace wise ... adjust your loading dies to suit.