M14 headspace

scout800

scout800

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I just measured my headspace on my norinco M14 with usgi barrel and bolt. It closed on a 308 win Field guage Snuggly (1.638), am I correct in assuming this is good for 7.62 nato headspace as the specs are different (1.635GO and 1.6455FIELD)? Also is it not that the headspace is long for 308win ammo but that the chamber is cut longer to keep the pressure down for the 7.62 natos thicker casing? If I look at the specs for the Nato round my headspace seems to be right where it should be, and would make sense since it is Nato spec parts.

Thanks
 
Thanks, thats what I thought, but another question is, is it OK to shoot commercal 308? I would think so since the long headspace is due to a long chamber and not a set-back bolt causing an unsupported web. Am I correct? Also with a longer chamber would it cause the brass to fatige at the web from repeated streching and resizing?
 
Is the barrel and bolt well used? If they are not I am surprised that your headspace is so big. My bolt was lapped to "dead nuts Saami" as Hungry puts it. I used a new barrel and used bolt. Maybe you can elaborate on "fits snug on go/no go guage. A "snug" fit differs between most people. I used Forster NM headspace guages to lap mine so I know the exact measurement.

Hooligan
 
Snug to me was being able to lock it up with a little force, and not bind. the barrel I can see has some throat erosion and looks to have a few miles on it, the bolt doesn't look worn at all and when in lockup with the above barrel has very little front to back movement. What kind of barrel did you put on?
 
If brass is being fireformed in a generous spec. chamber, and then full length sized back to basic SAAMI specs., its going to get worked pretty seriously. By the same token, reloads for a rifle like a 305 MUST chamber freely. If they hang up, there is a risk of an unlocked discharge. Generous headspace can result from a deep chamber, or a set back bolt. Obviously you don't want too much case out of the chamber. As far as that goes, you can have perfect headspace when the bolt doesn't come within half an inch of the breech. For a rifle to be set up properly, there are a number of considerations - headspace, breeching, etc. For what its worth, my 305, original except for TRW bolt, can be closed on a SAAMI NO GO (I can thumb push the rh lug down to lock). It will not accept a SAAMI FIELD. With the original bolt, it would accept the FIELD easily.
 
Very nice, where did you get it? How much if you dont mind? You should post a pic. The barrel you have is likely chambered for .308Win right? The barrel I put on was a USGI made in '60 chambered for 7.62x51, hence the reason the headspace is long by SAAMI specs.
 
Oops, barrel is criterion not centurion. $350 rings a bell from GGFB (Girls, Guns and Fast Bikes) Looks awesome with navy sights and Vortex fh. Sorry, no digital camera yet. Too much money goes to guns. Can't remember if it is 308 or 7.62 and it is scoped at the moment so I can't take a look right now. Even with the generously headspaced Norinco chambers with a newish bolt you can get it or close to "dead nuts SAAMI". Maybe you should try another bolt if you have any around.
 
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