Of interest on this point, when the Aust Army re introduced the No1 MkIII* HT sniper rifle into service as an interim measure in the 1970's, the parts list included a selection of measured bolt heads to provide a quick and easy fix for headspace.
I found this chart quite valuable so I took the liberty of quickly transcribing it and reposting as a crisp document format for all to keep.
Interesting there is no number "8" 0.638" bolt head in the selection.
Last edited by Sentryduty; 02-04-2016 at 10:43 AM.
- Darren 1 PL West Nova Scotia Regiment 2000-2003
1 BN Princess Patricia's Canadian Light Infantry 2003-2013