No.4 bolt heads specifications

[Ridolpho]

Thanks Bow for asking a question I've been wanting to ask (ie. why doesn't someone build some new large size bolt heads?) and thanks to everyone else for answering said question! My specific rifle of interest is a 43 Longbranch that had one of the 6 groove barrels installed in the 50's and in very good condition. It headspaces (and shoots) OK but the bolt head measures 0.642 leading me to wonder where I would go from there if I shoot it a bunch and it opens up.

Ridolpho

Information

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[Alan de Enfield]

Here is an extract from a detailed 'thesis' By Peter Laidler on Headspace.
You can find the full article in the Milsurps Library.

If you cannot get headspace, even using the very relaxed criteria I have discussed here by using a new bolt and a No3 bolt head, then I’m afraid that it means your body is knackered. This quaint old Armourers technical term indicates that it’s seen better days ….., it’s xxxxed! You COULD allow yourself up to, say, .078” headspace but the technical opinion reached during research into this during the 50’s is that it’s a palliative and not a true cure.