I know a person can switch a Savage barrel, and set the head space with barrel nut, without going to the Gunsmith to do this task. I was talking to a professional shooter this weekend at the f-class shoot, and he had a Panda action. He was telling me that with a Panda action there are plenty of gunsmiths he can send a barrel to have it chambered, and the head space be perfect, without sending him the action. He also told me a person could switch bolts without changing head space. Is this correct? How do you set head space with these action?