Headspace failure - need advice

[LRRPF52]

Gas guns need some slop in the chamber to reliably function.

What are your bolt lug lengths?

If it chambers and fires live factory ammunition without issue, I would move on.

I measure headspace with fired cases after pre-checking the chamber with various dummy cartridges I have for that purpose.

I use a spare, stripped bolt for that, which has .136” face depth and the same lug lengths as my others.

I use that bolt to test my die set-up as well. Loaded cartridges need to be able to chamber and allow clear bolt closure.

I’ve never used any chamber gauges on 6.5 Grendel for that reason.

The loaded cartridges and spent brass don’t lie.