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Jonk, or anybody

tccox
I didn't want to hijack your thread on the experts about the NR1 Mk III* rifle. I have an Australian one. How do you determine headspace? I have not yet fired mine but plan to in near future. Mine appears to be in good mechanical order. What will excessive headspace do to a fired case? Any input from anyone will be appreciated. Tom
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  • tccox
    ANYONE??
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  • jonk
    Well headspace is best determined with a headspace gauge. They come in 3 flavors- go, no go, and field. The first two are pretty much self-explanatory; the last is kind of a 'rough and ready' gauge- if it closes on a no-go gauge, that doesn't totally mean it is lost- but if it closes on a field gauge, it is a bad sign.

    That said: if you fire the gun from a tire or other support via string the first time, examining the brass can tell you a lot. Was there any primer back out? Is there a shiny ring or bulge near case head? Compare the shoulder position on the fired round to a factory fresh case; did the shoulder move forward significantly? Any of these may indicate excessive headspace and/or a loose chamber.

    I've had over 100 milsurps in my posession at one time or another, and have had headspace issues on exactly two- the Enfield being one. So it isn't that common, and not the end of the world, either. If you reload, you can get around a headspace problem easily enough. Seat a long cast bullet so that it crushes against the rifling- i.e. out a long way- with a very light powder charge. 10 gr of Red dot is what I use. This will ensure that the rim of the case is flush against the bolt despite the headspace problem- which on an Enfield or other rimmed round would be excess play between the bolt face and the chamber face, i.e. thicker than the rim itself. Fire this, and the shoulder will blow out to fit your chamber exactly, and neck size reloads only. This will ensure further loadings headspace on the shoulder rather than the rim.

    Depending on how severe your headspace problem is, this may or may not help. If the web area right ahead of the rim is unsupported, you still may get a case seperation there. This could also result from a gun that actually has quite good headspace, but an oversized chamber.

    In my case the gun has both, and I think I'm just going to sell it for whatever I can get for it. It would be fine to part out, or as a gunsmith project, or just to shoot with light loads and cast bullets.
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