Getting An M1/M14 Headspace 'In Spec'

givette

June 08, 2012 12:52

So, you re-barrel. Index the splines correctly for the gas-cylinder. Then you check the chamber with the appropriate gauges.

The headspace is out of spec!

Now what? I'm thinking the only way to go is another barrel. If not, just where, and what do you adjust?

Thanks, Joe

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  cpermd

  June 08, 2012 14:07

  Chromelined barrel?
  
  Change bolts

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  M1A762

  June 08, 2012 14:11

  How far out from spec is it?
  
  Is it a matter of lapping the bolt or is the headspace not even
  close?
  
  I think I read that the shoulder of the barrel can be turned down, but then there can be indexing problems, it is trial and error.

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  givette

  June 08, 2012 15:12

  It's the barrel. Headspace gauge sits a few thousandth's deeper in the replacement barrel, than on the original. Chamber shoulder way too deep.
  
  I'm going to re-barrel. Since the splines have to be indexed to true vertical, there's no shank alteration leeway as on a tapered cylinder barrel-blank. I've come to the conclusion that this type of firearm is either in [spec], or it's not. Thanks, Joe

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  nmyers

  June 09, 2012 04:32

  Joe, it's not that simple.
  
  You failed to tell us what make receiver, bolt, & barrel you have. I assume that your receiver is commercial, &, as we all know, NO M14-type receiver is made to USGI specs. A service trained armorer will have the gauges to evaluate the parts & determine how to compensate for any problems, including the likelihood that a new barrel is short chambered.
  
  Dean's Gun Restorations? Fulton Armory? James River Armory? There are a bunch of places who should be able to do the job for you.
  
  Neal

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  givette

  June 09, 2012 05:47

  Thanks, Neal. I pulled the 2nd barrel, and it's out of spec. I can visually note that each gauge (go/no-go/field) sits deeper into the barrel end (chamber mouth) than the original.
  
  The barrel I bought many years ago, and I think it's a cheap Chinese knockoff, or sumsuch. Can't see any markings!
  
  And, the receiver is an LRB commercial (no selector lug, and no connector notch-otherwise dimensionally 'in spec'), and it has a TRW bolt. Don't want to mess with those!
  
  The kicker is (and this is my laziness showing[B)] is that I have an unfired Obermeyer 5r/11.25 barrel down in Florida (I'm in New York). I'll see if I can get it sent up to me. Oy Vey!
  
  Best, Joe

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  Emmett Dunham

  June 09, 2012 17:20

  I don't understand what you mean by see the gage sets down farther? The only thing you should be able to see is if the bolt lug does or does not close one the gages? There is no measurement that can be taken unless you are a machinist with tool and confirm that anything in the chamber is .001 off?
  
  Good, luck with the other barrel!
  
  Emmett

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