I feel I got it right on my .300 Win Mag build. I was a little apprehensive at setting the headspace but it was not that tough.

Put in the go guage closed the bolt, threaded the barrel in until it stopped, tightend the barrel nut to 60 foot pounds, removed the go guage and added a piece of tape and placed the go guage back in the chamber and the bolt would not close.

I then chambered a round, removed it and added one piece of tape and tried to close the bolt, it closed but was very tight. I removed the round and added a second piece of tape and tried to chamber the round and the bolt would not close.

To satisfy myself I then did the same exact proceedure above on a factory headspaced .243 savage 110 that I have. The results were exactly the same on the .243 as on the .300 Win Mag.

If I missed anything or did anything incorrectly please let me know. I just mounted up a Leupold VariXIII and I am off to the range tomorrow morning to see how it shoots. Thanks!