.............I don't know of a convenient to me gunsmith that might be able to take an exact measurement of the internal headspace.
Cheers, ATB
HS gauges for the 6.5 55 are not available is a series, only the usual g/ng/f
The only sets which are generally available are for the 308/7.62 series and derivatives, this is for two reasons:
- The rather obvious 308 vs 7.62 headspace difference - so OK to use 7.62 in a 308 chamber but not 308 ammo in a 7.62 gun etc
- Traditionally the custom target rifles tended to be based on 308 cases , so if you built a custom rifle, you would headspace down to the bottom end of the acceptable range – hence why 308/7.62 HS gauges can be obtained in a series.
This second point also guides you on the approximate HS your gun will have, if it is a custom target version, it will usually be headspaced around the bottom end – so typically a little over the go gauge (1.7794) – say 1.780 – 1.781, if however it is a general or stalking rifle, it would be headspaced towards the no go (1.785) to ensure it’s “less fussy about ammo or cases” – say 1.783 being a sauer 1.785 if it was Ruger etc
Of course this is when new – after manufacture when it has been used a lot, most guns headspace well above the no-go gauge – which is OK as long as it is below field (1.789) – so it depends on the gun and usage/age
These days custom target rifles don’t tend to be based on 308 cases anymore and are usually some wildcat derivative – in which case we use a different technique for headspace measurement – which you may use
Basically it is usual when building a custom target rifle in some odd wildcat based cartridge to only have the go gauge manufactured, and when chambering just ensure it goes, then for the no go just add packing – Rizla paper comes in various thicknesses, so if you use the silver it is around 0.8 mill thick – about 0.02mm – so using two silver Rizla papers on the head of the headspace gauge will change the 6.5 x 55 go (1.7794) to 1.781!
In your case, if you use a tight (ish) case and add packing – draw the paper over your jumper/trousers and it will receive enough static to stick to the case head – add pieces until you generate a situation where it will/won’t go - say three papers will, four won’t then use your current measuring method (I assume you are using the hornady Cart HS kit) – which will give you the range as say 1.7832 will go whilst 1.784 won’t.
Unfortunately there are a few downsides here – firstly the Hornady kit is designed to be used with a Vernier or digital calliper – the digital’s aren’t that accurate – only to 1-2 mill or so, and although verniers are available much more accurate they are very expensive and not the usual ones available, so you do need to use a micrometer to measure, and secondly be careful about the paper – it can stick to the bolt face (so when you measure it you miss a couple of thicknesses), or you fold it over and miss a thickness, or you can compress the paper with the bolt – so limit the number of papers to 3 or so
Julie