Savage head spacing system


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Marintime Mike
November 30, 2007, 04:08 PM
Sorry if this perennial problem bores you folks....but maybe someone can clear me up on this..
I have a rifle supposedly chambered for 7.62 NATO....and of course I want to shoot commercial .308 Winchester in it....
I had the head space checked with .308 SAAMI guages and the bolt closes on the GO guage...and won't QUITE close on the Field Reject.....1.0030 and 1.0038.
I don't intend to shoot reloads in it so it should be fine as is..but...the rifle has that Savage barrel lock head spacing system..
I was thinking of having a gunsmith tighten the thing up a bit to get it more in line with SAAMI .308 specs...That is ...shorten the chamber a bit...
As I understand it...the Nato 7.62 chamber is made purposefully a bit large to accomodate variations in military ammo...so they all will at least chamber...they get away with this because the brass is thicker and can take the extra expansion..but I probably wouldn't be firing mil surp ammo anyway.
Is my thinking correct on this....would the head space adjustment do what I want ?....How much is involved in this...
Thnx...
Oh...the action is considerably strengthened and their should be no problems with pressures...

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DnPRK
November 30, 2007, 04:32 PM
Your measurements don't make sense.
SAAMI 308; GO=1.630, NO GO=1.634, Field=1.638
7.62 NATO; GO=1.635, NO GO=1.6385, Field=1.6455

As you can see, there is a big overlap between SAAMI and NATO chamber dimensional specs. The concern with shooting commercial ammo in a NATO chamber is proper functioning of the gas system in semi-auto and full-auto military rifles and machine guns. The gas system in a NATO SA/FA firearm is tuned with specific pressures (50,000 psi) required to unlock the bolt and act against the operating spring without undue battering of the mechanism.

Commercial bolt action rifles have no such gas balance requirement and are allowed pressures up to 62,000 psi. In short, some commercial ammo (typically heavy bullet hunting loads) can cause battering of NATO SA/FA components such as operating rods and bolts/bolt carriers. If you stick with commercial loads sold to duplicate M80 ball, you shouldn't have any problem.

If you reload, stick with medium burning rate powders for your NATO gas operated gun.

The Savage headspacing system is extremely easy to adjust. Loosen the barrel nut. Insert GO gage into the chamber. Hand tighten the barrel (snug, not hard) against the gage. Tighten the barrel nut, which will loosen the headspace by about 0.001". The worst that will happen is any barrel-mounted sights may appear slightly canted.

rcmodel
November 30, 2007, 04:45 PM
If you are only going to shoot new commercial .308 ammo in it, excess headspace shortening your case life is not a concern.

If you are going to handload, you can adjust your headspace with the sizing die to fit your rifle.

So, I wouldn't mess with it.
Just go shooting.

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

Marintime Mike
November 30, 2007, 05:15 PM
Thnx guys....I was going on memory for those guages and of course got them wrong....Saami Go for .308 is 1.630....Field reject is 1.638 and NO GO is whatever the guage manufacturer decides it is...some have 1.634 others 1.636
This thing is a bolt action ...so I'm not concerned with what it might do to a self loader...

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