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Headspace issues M1918 BAR Winchester


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#1 Rebel Rifle Ordnance LLC

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Posted 27 January 2016 - 11:31 AM

I've got a M1918 Winchester BAR that was converted to an A2.  I'm in the process of making it all original to M1918.  I bought a barrel from someone at Knob Creek, installed it and the headspace failed.  I gauged the TE and both the barrel that was on it and the barrel I bought were 3 and 5 respectively.  So, I got a new barrel.  Put that.  Head space fails according to method used here Page 11 in PDF: http://www.forgotten... bar manual.pdf

 

See pic's.

 

I have a NESA that I used for reference.  Using the same field gauge, same bolt linkage, my NESA passes, the Winchester fails.   I'm trying to figure out what I need to do to fix this.  Are there different size bolts I can use?  

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Edited by Rebel Rifle Ordnance LLC, 27 January 2016 - 11:31 AM.

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#2 RoscoeTurner

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Posted 27 January 2016 - 09:12 PM

I suggest giving OOW a call to see if they can help otherwise maybe send the barrel and receiver to them to inspect.


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#3 emmagee1917

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Posted 28 January 2016 - 02:46 PM

BARs lock up at the rear of the hump in the top of the reciever . The part of the bolt that pivots up into that can be changed out with a NIB one to tighten it up . The rear surface of the pivoting piece can be built up / filed down to fit .

Chris


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#4 AlexanderA

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Posted 30 January 2016 - 10:21 AM

Is the headspace too loose, or too tight? Typically, when using new parts, the headspace will be too tight. This is adjusted by careful grinding on the rear bearing surface of the bolt lock (the pivoting piece attached to the bolt). Some newer bolt locks have a dovetailed insert on the bearing surface, that can be replaced (if it's ground down too far).

 

In the unlikely event the headspace is too loose, you have to try different bolt locks. In the absoloute worst-case scenario, you may have to face off the barrel shoulder in a lathe, and set the barrel back in the receiver one full turn (the extractor cut and the indexing marks have to line up). 


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#5 Annihilator

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Posted 30 January 2016 - 12:25 PM

If you set the barrel back one turn you will have a problem with the gas port hole of the barrel no more in line with the hole on the gas tube


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#6 AlexanderA

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Posted 30 January 2016 - 12:43 PM

That's true. You don't want to set the barrel back if you can help it. Just find a longer bolt lock.


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#7 m35cargo

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Posted 01 February 2016 - 06:55 PM

I had same problem when I rebarreled mine. On the old barrel the headspace was plus 4 and when I put the new barrel on it was tight. I had a parts kit so I tried that bolt  and the headspace was perfect. If you have access to another bolt, try it.


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#8 deerslayer

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Posted 10 April 2016 - 09:36 PM

I've built up a bolt toggle by welding to fix long headspace and cut a chamber deeper to fix short. So either way you can fix if trying another bolt does not work.
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#9 Springman

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Posted 29 June 2018 - 04:52 PM

I know this is a old post, it has been helpful to the point I am at now, after setting head spacing by removing material from the back of the bolt I tried to test fire and I have deep primer strikes and the last 1/4 in. of the shell is swelled up, the gun will not cycle because the cartridge is tight after firing. so I am assuming its firing before the shell is completely seated in the barrel. Whats the next step? All help is greatly appreciated.


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#10 Rebel Rifle Ordnance LLC

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Posted 29 June 2018 - 05:05 PM

I know this is a old post, it has been helpful to the point I am at now, after setting head spacing by removing material from the back of the bolt I tried to test fire and I have deep primer strikes and the last 1/4 in. of the shell is swelled up, the gun will not cycle because the cartridge is tight after firing. so I am assuming its firing before the shell is completely seated in the barrel. Whats the next step? All help is greatly appreciated.

 

Did you check the headspace according to my original post using the link to the original manual?  That method is fool proof.  These guns don't need super accurate head space to run.  A little loose causes no issues but too loose and you end up with problems.  Don't start grinding material off until you know 100% and even then it's better to try different bolt and bolt link combinations before you start removing material which is never a good idea.  You can't remove the material evenly unless you are doing it on a mill and there are multiple places on the bolt and bolt link that could be causing tight head space not just the rear.   If you took off too much or too much in the wrong place and it sounds like that is what has happened, you'll need to start over with another bolt and / or bolt link depending on where or what you ground off.  Where are you removing material from?  The back is not always where it needs to be removed.  The bolt also can be too tight from the two walls on top of the bolt link that sits in the top of the receiver as well as spacing of the pin that holds the bolt and link together.  Stop check the head space according to my original post and see if you are too loose.  If so, order another bolt that you jimmied with and put it with the bolt link and check it again.  I have a lot of bolts and links and can probably get the correct combination but I'd have to have your gun to make sure as just a little change can make a big difference.


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#11 RoscoeTurner

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Posted 29 June 2018 - 05:36 PM

Cannot find a reference in any of the original manuals where a grinder is used as a solution to headspace problems.


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#12 Springman

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Posted 29 June 2018 - 05:59 PM

Thanks for the help, When I first received the rifle the link pin was missing. I ordered the link pin but with the link pin installed then the hammer block pin could not be installed through the peep hole, I could install it through the slotted side but as you know you can not install the charging handle unless the hammer pin can come through the peep hole. I the searched until I found this post. First I remove 5 thou from the back fo the bolt lock [milled on Bridgeport ] then a few off the top rails [just surfaced ] after that I was able to install pin though peep hole,  with firing pin removed and a empty shell installed in the barrel the hammer pin is as pictured in this photo. I am wonder if firing pin could be to long.

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Edited by Springman, 29 June 2018 - 06:02 PM.

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#13 Rebel Rifle Ordnance LLC

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Posted 29 June 2018 - 06:55 PM

I don't know but I wouldn't take any more material off.  Setting the headspace is done by using different combinations of bolt and bolt links.  If you are having problems with the pin going into the bolt that's another issue not related to head space.  You may have a Swedish BAR and those bolts are not interchangeable.  Somin ain't right and it's got to be a combination of parts being used most likely Swedish parts.


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#14 Springman

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Posted 29 June 2018 - 07:05 PM

I don't know but I wouldn't take any more material off.  Setting the headspace is done by using different combinations of bolt and bolt links.  If you are having problems with the pin going into the bolt that's another issue not related to head space.  You may have a Swedish BAR and those bolts are not interchangeable.  Somin ain't right and it's got to be a combination of parts being used most likely Swedish parts.

 

The BAR is NESA , I agree head spacing is correct, I am thinking firing pin is to long and causing a early fire, which is causing the shell to swell. I will look at bolt to try to identify that it is also NESA. thanks


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#15 RoscoeTurner

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Posted 29 June 2018 - 07:51 PM

TM 9-1005-208-35

4. Correcting Headspace.
 
a. Insufficient or excessive headspace is usually corrected by the
replacement of the bolt. If excessive headspace cannot be corrected
by replacement of new bolt assembly of maximum length, the cause
lies elsewhere. It could be caused by excessive wear in locking
recess of receiver.
(1) Rebarrel if necessary; use breechbore gage 5564343.
(2) See paragraph 1, for breech bore gage limitations.
b. If placement of new bolt and/or rebarreling does not correct
headspace, return new bolt to stock and evacuate unserviceable
weapon to depot maintenance.

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#16 jim c 351

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Posted 30 June 2018 - 01:10 PM

FWIW,

Page 329 of the Jim Ballou book shows a headspace adjusting plate ,installed in the bolt lock and ground to fit.

Jim C


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#17 Springman

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Posted 05 July 2018 - 04:33 PM

I found that after I had the correct head spacing , my gas piston was out of spec. passed right through  the no go gauge. I fabricated a new  piston and the gun runs  again.


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#18 Rebel Rifle Ordnance LLC

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Posted 06 July 2018 - 06:24 PM

I found that after I had the correct head spacing , my gas piston was out of spec. passed right through  the no go gauge. I fabricated a new  piston and the gun runs  again.

OOW has new gas pistons.  I replaced all mine on my BAR's.  They aren't too bad, like $75 or so a piece I think.


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