Pre-66 110L headspacing issues

Hello all,

I have a pre-66 110L in .308 that has been a great shooter for years. Recently the groupings went to the size of a watermelon. Low and behold, my barrel had worked loose! The barrel has a hump and iron sights, and barrel nut FYI.

Fast forward reading many posts on here, I buy a .308 headspacing set.

here is where I’m at..

go gauge in, head spacing doesn’t line up with iron sights. It’s about 90 degrees off, bolt will not shut with iron sights lined up. I back out 270 degrees to line up iron sights once again... field gauge chambers with ease.

The bolt is the old style extractor and I have not taken it apart. This might be why the go gauge won’t close on the tighter barrel position. I’ve searched extensively for a tutorial of disassembly. Any one know how?

second, knowing the iron sights were lined up previously, should I position the barrel in the tighter position, take it to the range and let it rip knowing the go gauge had an issue (possible due to extractor)?


I love the rifle as is, and would love to not rebarrel with new bolt etc.

thanks in advance!

Make certain the gauge is seated against the bolt head and the extractor is out of the way.

Every turn on your barrel is .050". A quarter turn or 90* means that you are somewhere over .010" too long, as exactly 90* would be .0125" too long. If you reload the factory setting could work. If you are shooting factory ammo I would expect some issues with light primer strikes at some point. Possibly case head separation. Personally I would pull the sights and headspace it correctly and see what happens.

If it is 270* off that means you may be .037" too long.

If you check headspace and pull the bolt back and the gauge extracts then it has slipped over the extractor.

I would try the "tight" setting with sights aligned as they should be, then try and see if the bolt will close on your fired cases or better yet new unfired brass. Another alternative is having a smith ream the chamber a hair deeper (if you can find one to do that).
Other alternative if you use a scope exclusively is to remove & pug the iron sights.
Good luck,
Randy

V:

Thank you both for the great responses. Unfortunately (maybe?) it’s old enough that the rear sight is a bulb in the barrel. It will never look right if it is not aligned.

I did torque the barrel down at the tighter setting and the bolt closes with fired brass. Good sign! I’ll take it out this weekend and see if new brass chambers and fired.

I thought about having the barrel reamed but I kept falling back on the fact that it has been shot for 60 years with this barrel and fairly accurately. That’s all I’m looking for. With your guys’ advice it sounds like I’ll be good to go. I’ll report back.

thanks!

That's the thing with pre-66 barrels, the barrel band and monster dovetail for the rear sight really doesn't leave much room for "adjustment" if you wish to retain and use the original open sights.

I do love the look of the classic dovetail even though I have optics mounted above.

Good news and bad news. The rifle is chambering Unfired rounds just fine at the tighter setting.

Bad news is I found a small crack in the barrel nut. I’m thinking this is what led to the loose barrel to begin with. Are these nuts interchangeable with all small shank nuts?!

All the small shank nuts have the same thread. The crack you found certainly could explain the nut coming loose as I've never seen it and only heard about it once or twice.
Is there any explanation for the nut "cracking" ? Would it be possible to get a picture? Curious.
Keep us posted

It's not uncommon for the old style nuts to crack right in one of the grooves. The old nuts have a radius-ed groove that is deeper than the square bottomed groove of current production.

Quote:

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Originally Posted by fostrem

I do love the look of the classic dovetail even though I have optics mounted above.

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No argument from me on that! :cool: