Re: 338 edge headspace gauge
Sorry, not into 'hero' worship. As a general rule of 'practice' in my shop I cut SAMMI tolerances in half for headspacing. I'll continue to trust my Starrett depth mic' and my ability to use it rather than a piece of Scoth Tape, to know where I'm at within that tolerance. I've got a couple of rolls in the office, couldn't find a NIST certification anywhere! By the way, I've built quit a few competition rifles in my day, too.
"Shoots real good!": definition; it didn't blow-up in my face.