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Discussion Starter · #1 · (Edited)
The following is meant for M1A/ M14/ M1's ...

I don't have a good deal of confidence in reported Head space [HS] numbers, after all, Ripsaw may have done it.. That's nasty, I take it back..

Every rifle's chamber is unique, along with the Lug shoulders and Bolt fit.. Knowing the HS reading is important if you are a accuracy seeker,,, if nothing else, to be safe..

A case in point. My newest barrel came with a HS tag stating a 1.632" HS number.... Well, it may have been on their HS gauges and their Bolt, but on my gauges and bolt is was less than 1.629".. Now what?

My case head space desired number is .004" to .006" under chamber HS.. There was no starting point.. There is a way to solve this rather common issue..

Fed 308 Win. cases are all I use, that makes a difference , cases size differently from one brand to another. Select the case brand you use the most..

Selecting about 20 good looking Fed cases fired in rifle to be used. Sized the first one with a loose small base die, it came out at 1.631", that will not work, turning the die tighter, the second case sized came out at 1.628", now there is place to start.

Stripped rifle and cleaned the chamber and bolt, removed all lube, wiped with actone all contact surfaces. The 1.628' would not allow the bolt to drop without good stiff finger pressure. Repeated the same as above, and produced a case HS with 1.624", a very slight drag, not what I want. the next case came out at 1.622", a perfect number in my Camp,,, bolt dropped freely and completely,you can hear the click. And that is exactly what I was looking for..

Tried to close the 1.622" case on two other bolts, newer, and neither would go to my needs. This procedure took a couple of hours, well worth the time, when winning, my Buddy has to pay for Lunch... Art L
 

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Art,

There are some options that come to my mind: Find out what brand of headspace gages were initially used to measure the headspace. It has been my understanding that readings can vary depending on what brand of gages were used; try different bolts in your rifle with the headspace gages; keep the bolt you are using and ream the chamber further to achieve desired headspace.

If I am off base with these ideas, someone please correct me. That's as far as my thinking takes me.
 

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Discussion Starter · #3 ·
Your not off base..

Art,

There are some options that come to my mind: Find out what brand of headspace gages were initially used to measure the headspace. It has been my understanding that readings can vary depending on what brand of gages were used; try different bolts in your rifle with the headspace gages; keep the bolt you are using and ream the chamber further to achieve desired headspace.

If I am off base with these ideas, someone please correct me. That's as far as my thinking takes me.


That is good suggestion, the problem is , do like to put a foreign reamer in a Match chamber.. Also, it means addition costs and a waiting period..

Thank you anyhow..

How are you readers replying before I've finished writing the Thread.. Art L.
 

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I don't understand a new barrel coming with a precise HS number.
Unless the number on the hang-tag was a suggestion for what the installed HS should be set at.
Was this on a really 'new never installed barrel' or a 'take-off' barrel that had already been installed and HS'd on a receiver/bolt?

For chro-moly or SS barrels, I thought they usually came 'short chambered' and the installer would set the final installed HS with a finish reamer.

Jay Kosta
Endwell NY USA
 

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You might find one of the new custom length bolts from Bula Defense suited to your situation. They are available -.006 to + .006 with a 0 being standard spec. lug to bolt face. These critters should be able to cure a world of combinations. Jeff just previewed their armorers bolt kit at Camp Perry three weeks ago.
With a standard bolt headspacing at 1.629, if your were to use a -.002 = 1.631, -.004 = 1.633, and -.006 = 1.635. May not work exactly in your situation, but there is hope Art. Worth a look.

[URL=http://s1180.photobucket.com/user/nf1e/media/IMG_0553_zpshw2pildx.jpg.html][/URL]

Semper Fi
Art
 
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