I'm what you may call a hobby gunsmith. I chamber and thread my own barrels and occasionally for friends too. Normally I set my head space using the action. If I am going to make a "pre-fit" barrel without the action, what is the best way to measure from the shoulder to the back of the go guage? Obviously I will have the required dimensions of the action on hand. I have found using a depth mic placed on the back of the go guage and then coming down to the shoulder to be pretty inconsistent for me. I thought about making a tube that slides over the thread tenon and rests on the shoulder and comes out past the go gauge, so I can place my depth mic on the tube then measure down to the go guage. Interested to learn what works best for this measurement.