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Posted: 12/10/2006 12:28:27 AM EDT
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ok... help out the ignorant here... in simple terms how do you "headspace" a bolt, and what exactly does it do? seems like its to make sure the bullet seats all the way in the chamber? is it adjustable with the right tools? |
I re-read your post, and realized I had not answered part of your question. Headspace is a tolerance. It is the distance between the breechface and a datum line, in this case defined as a point on the middle of the shoulder of the case. If the gun's headspacing is too tight, the case when in battery can be a crush fit causing jams or failure to go into battery. If the headspace is too generous, then you can have case head seperations due to too much stretching of the brass. While 7.62x51 and .308 Nato cases look identical, the Nato chamber specs are more generous in allowance for headspace. Since military brass is loaded normally in thicker brass, it is more resistant to case head seperation. Another problem with the differences in headspace specs, is for those who reload. If you resize a case fired in a gun with overly generous headspace, odds are it will seperate quickly. When you talk about the Chinese guns, it's sometimes possible to crank the barrel in just a bit more to tighten up the headspace. It's only because some are not properly indexed that this is an option at all. The other option is to fit in a new bolt which might tighten it up. If you shoot surplus ammo, this isn't really a problem. If you reload, it's worth investigating. |
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