New 6.5G build. What about head spacing gauges?

[grayfox]

Let me add another thing. For my AR-Grendels I built there was no need to check head space, they were reputable mfrs and that is all set by the barrel+barrel extension, and bolt. The barrel/extension is already assembled from the mfr and so the only remaining piece is proper matching bolt face depth to the 0.125 or 0.136- as required by the specific barrel you got.