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OOW receiver kit barrel installation


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#1 1bid_1kill

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Posted 06 May 2018 - 03:20 PM

I just received a 1918A3 receiver kit from OOW.  Been wanting one for a long time, and finally decided to pull the trigger. 

 

I have a question regarding installing a barrel.  I have a NOS HSA barrel I would like to install.  When I hand tighten the barrel to the point where the shoulder is making contact with the face of the receiver, there is 25° of draw between the witness marks (in other words "a lot").  Anybody had a similar experience with their build?  Is it normal to have to remove material from USGI barrels shoulder to get proper timing with these receivers?

 

Thanks!


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#2 Black River Militaria CII

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Posted 06 May 2018 - 09:48 PM

Really not enough info about what you have for a barrel, etc to make more than general suggestions about how to get it properly installed.Ignore the old witness marks.Does the correct alignment of the barrel require further tightening or loosening of the barrel? I assume the breechface cutouts have been machined already, so the following will apply. The breechface cutout for the extractor and the lefthand cutaway of the feedramp to allow the bolt to go fully into battery are the important guides to correct installation. The horizontal cut of the feedramp to the left of the breech should be at the same height or within close tolerance to the top of the left rail. If this cutaway is in the correct position the extractor cutout will also be in the correct position. With these cutouts in the correct position the headspace and the bolt lockup both should be correct. You cannot cut the shoulder of the barrel and move the barrel further into the receiver and still have correct bolt lockup specs. Moving the barrel further into the receiver will prevent the bolt from locking up and the locking shoulder or the lock face will have to be adjusted for the shorter distance.
So, if the barrel over rotates for full tightening past the correct alignment, you will have to shim it. If it underrotates for full tightening then you will have to determine what degree of rotation fully tightens the barrel and cut the shoulder to create under rotation when hand tightned and then the further distance for full tightening where the cutouts are in correct alignmenf.
The above is the result of my experience with replacing BAR barrels and others might have different suggestions.
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#3 Joe H

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Posted 07 May 2018 - 07:03 AM

1bid,

 

I recently installed a NESA 1944 GI barrel on a semi BAR I had built using a Philly Ord receiver. Tightening the barrel on the receiver I came up maybe 16-20 degrees short of the barrel being in the correct position (wrench tight). Can't remember the exact degrees but using the thread pitch on the barrel I needed to remove about .003" from the barrel shoulder (not the face of the receiver). My newly machined receiver of course had no witness mark so I used the same procedure as a garand barrel using levels on the receiver and the front sight. I used a small swiss file and carefully filed the barrel shoulder till I got the right fit. File and try, didn't take very long. I was afraid to use a lathe because of the small amount of removal. The filing worked well. I would do the same next time.

 

I have a 1952 ROTA barrel and a PO receiver for a future build. Initial fit is same as above.

 

I think I remember a post somewhere indicating my experience is pretty typical of the Ohio Ord fit up.

 

                                                     Joe  


Edited by Joe H, 07 May 2018 - 07:05 AM.

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#4 1bid_1kill

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Posted 07 May 2018 - 06:28 PM

Thanks for the replies, very informative.  I'm determining degrees of draw by using a magnetic angle finder on the front sight block.  If this were an M1 or an M14, I'd shoot for 10-15° of draw hand tight before using a receiver wrench to bring into time.  Does this sound about right for a BAR barrel as well? 

 

I don't have access to a lathe, and don't have a lot of experience using a file to remove thousandths of an inch of material.  Is there a trick to keeping the material removal uniform around the shoulder?

 

What barrel vise do you use for BAR barrels?

 

Thanks again for the help.


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#5 jl7422

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Posted 07 May 2018 - 09:06 PM

Play it safe. . . send it to OOW and have them do it and check headspace while they're at it. 


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#6 Joe H

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Posted 08 May 2018 - 06:40 AM

I don't have access to a lathe, and don't have a lot of experience using a file to remove thousandths of an inch of material.  Is there a trick to keeping the material removal uniform around the shoulder?

 

What barrel vise do you use for BAR barrels?

1id,

 

My experience with the Philly Ord receivers and a GI barrel is that wrench tight you will still be short around 15 deg. The filing is evenly distributed around the circumference. I made my own aluminum blocks with a rosin wrap (Al. will mar the finish) for the barrel to fit in my shop vise. Turned the receiver on with a stillson wrench with leather facing. The wrench must be on the very end of the receiver at the barrel. It is very easy to twist the BAR receiver if you are not careful.

 

I left the receiver locking face .008" proud so I could set the headspace after the GI barrel was in place. I don't know how OOW does the headspace on the receivers.

 

Considering all of the above I think j17422 has the right idea. If OOW will do it let them have at it. Once the barrel is in place it will be their problem to make the headspace right and I'm sure they have plenty of experience and equipment to do it. 

 

                                                 Joe 


Edited by Joe H, 08 May 2018 - 06:43 AM.

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#7 AlexanderA

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Posted 04 June 2018 - 11:35 AM

NOS GI barrels and new OOW receivers both have witness marks. If those witness marks are aligned, then the extractor cut, etc., will be in the right place. Headspace is then adjusted via the rear surface of the bolt lock (that bears against the locking recess in the receiver). Newer bolt locks have replaceable inserts for this purpose. On older ones, you use selective assembly, and/or grinding. (Grind on the bolt lock, not on the receiver.)
 
The important thing is to have the proper barrel wrench to exert enough torque on the barrel. At least one WW2 manual says to use a strap wrench, but that probably will slip before the barrel is tightened enough. As a last resort you might file a little off the barrel shoulder, but if you overdo it you'll have to shim the barrel.

Edited by AlexanderA, 04 June 2018 - 11:39 AM.

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