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  #1  
Old 07-06-2018, 07:12 PM
R6T8net R6T8net is offline
 
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Default 7-40 Barrel, Again

I have a barrel dated 7-40 and it has a radial ring machined just behind the lock threads and in front of the pads. I have never seen this feature before and was wondering if anyone can enlighten me. Bore is bright, muzzle looks good (buddy has my gauges so I cannot measure till tomorrow), breech is dark and itís been reparked; very nice specimen. Iím trying to decide between squirreling this away for a future project or selling to help fund Winchester barrel and stock.
https://imgur.com/gallery/SMZLVe5
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  #2  
Old 07-06-2018, 08:17 PM
krdomingue krdomingue is offline
 
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Not a gas trap, but the date puts it on the ragged edge of when they switch over to the gas port. I wonder if it is some sort of transitional design. Either that or somebody modified for some unknow purpose.
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Old 07-06-2018, 08:47 PM
R6T8net R6T8net is offline
 
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Doesn’t look modified but after all these years it’s really hard to tell.
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Old 07-07-2018, 05:26 AM
Mike in NC Mike in NC is online now
 
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The first gas port barrels were dated 6-40. That machined groove up front is something I haven't seen.

Quote:
Originally Posted by krdomingue View Post
Not a gas trap, but the date puts it on the ragged edge of when they switch over to the gas port. I wonder if it is some sort of transitional design. Either that or somebody modified for some unknow purpose.
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  #5  
Old 07-07-2018, 08:21 AM
bubba1 bubba1 is offline
 
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There are five known 6-40 barrels, three of which I've seen and have had the opportunity to inspect , and they all have this cut. Early 7-40 barrels also have this cut. I'm unsure how long they did this . I've seen one 1941 barrel with this cut also. It is unknown, at this time, what the purpose was for the cut /groove. Pretty cool though. Thanks for sharing.

Last edited by bubba1; 07-07-2018 at 08:24 AM.
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  #6  
Old 07-07-2018, 08:27 AM
Mark1 Mark1 is online now
 
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Could it be a thread stop. So the gas cylinder could not be set back any further so it would not interfere with the op rod bottoming out and hitting the gas nut?
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  #7  
Old 07-07-2018, 04:55 PM
jimthompson502002 jimthompson502002 is offline
 
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Location: La Crosse, Wisconsin
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I am by no means 100% sure, but the overall configuration looks like the 1940 tubes I had.

Also, since two of mine were brand new and even the threads/shank were phosphated virtually BLACK, I am not sure that isn't original finish. Of course, where they came from ( mine, I mean, purchased from a G.I. "source" who had no idea they were anything but scrap!), they might've been pulled from their tubes and refinished overall. But I'm inclined to doubt it.

Last edited by jimthompson502002; 07-09-2018 at 11:41 AM. Reason: clarification
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  #8  
Old 07-09-2018, 09:55 PM
airmech67 airmech67 is offline
 
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For what itís worth, my 8-40 barrel does not have the ring shown in the pics.
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  #9  
Old 07-10-2018, 07:59 AM
7,62x51mm 7,62x51mm is offline
 
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I have two mid 1940 rifles, both with S-A 7-40 dated barrels and neither have the extra cut on the threads
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  #10  
Old 07-11-2018, 09:40 PM
cav_cdr cav_cdr is offline
 
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Interesting. I haven't seen that before. Still learning. Thanks for sharing that.
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