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I lost all of my rifles & handguns in a mishap on Rio Grande when the barge hit a sandbar and sank.
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The Gas System are two clear ways.

#1, Drill, tap, screws and glue.

#2, As you noted above, welded.

DI5
 

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Pardon me as a newbie, how does tack weld comparing to tig weld? It was supposed to be pulled from match rifles, fwiw...
It could have been tacked welded by any means Mig, Tig or Ark. Unless you were there or told how you wouldn't know. Mig and Tig make for smaller cleaner weldments than Ark so my guess it was Miged or tiged.

Unitized gas cylinder are most common on Match rifles or rifles that the owner is seeking the upmost accuracy from.

Give it a good cleaning it up, and slide it on your rifle.
 

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That looks tack welded, too Me. And it looks small.
Should have done a better job of preventing the weld splatter from getting into the gas port area. IMO

Weld needs to be cleaned of slag to get a better look.

Trained in VWAC, Visual Weld Acceptance Criteria.

What's going on at the left side of the assembly, something on the barrel band?
 

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National Match gas cylinders have never been manufactured as such. All NM (unitized) gas cylinders were made up from standard parts modified to permanently attach the barrel band to the cylinder. As noted, some were welded (USN, USMC, USAF) and others were screwed together (ARMY). There is an actual government drawing of the assembly 9352735 which also happens to be the same number as the standard gas cylinder. The specification call for welding in accordance with SPEC MIL-W-8611. Why the ARMY chose to screw theirs together is unknown, but probably relates to welds having a higher failure rate. Of the hundreds that I have modified by the AMU method there have been no reports of failures of any kind. Except maybe those that were worn out... So, no they were not marked in any way to indicate they were NM spec. By the way, I've noted that original TRW NM M14 rifles did not come from the manufacturer with modified gas cylinders, NM spring guides, or reamed flash suppressors.
 

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Just a note on welding... If the rifle is being set up for service rifle matches, it must be welded from the inside so that the welds are not visible when the rifle is assembled. "external modification" rule. If it's for an EBR or some other use not covered by competition rules, the welds can be anywhere, as in EBRbuilder's photo.
 
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Discussion Starter · #13 ·
Is it common practice for nm gc to have some rubber sealant type subtance between the front band and the handguard? You can see that on the first picture, at top of the front band
 

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Is it common practice for nm gc to have some rubber sealant type subtance between the front band and the handguard? You can see that on the first picture, at top of the front band
It depends on who is building the rifle, but a lot of smiths will epoxy or silicone the front of the handguard to the front band. Not uncommon.
 

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In actual practice, unitized gas cylinders with exposed welds have always been allowed in sanctioned matches, even at Camp Perry. The CMP and NRA ignore this area as applied to the rules.
 

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That's interesting... I've never seen the spindle valve welded either - until now...
Screwing the band to the gas cylinder does of course immobilize the valve since the screws must be threaded into the valve stem. Having an adjustable valve may be desirable to some folks, but isn't important to most civilian shooters, at least from a practical standpoint. Not many of us fire off grenades, which was it's purpose. In competition shooting, the gas system must always be operational for semi-automatic fire.
 

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That looks tack welded, too Me. And it looks small.
This looks like a 'tack' weld to me, too. With a had held arc rod hence the 'slag'... Mig and Tig are usually gas shielded for cleaner welds.
This welder looks 'right handed' to me as the tack weld went left to right; I used to weld left handed and laid my beads right to left.
Could be a flux cored Mig wire weld though?
 

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Just a note on welding... If the rifle is being set up for service rifle matches, it must be welded from the inside so that the welds are not visible when the rifle is assembled. "external modification" rule.
In actual practice, unitized gas cylinders with exposed welds have always been allowed in sanctioned matches, even at Camp Perry. The CMP and NRA ignore this area as applied to the rules.
Ted is correct, I have never seen a rifle unk'ed for visible weldments of the gas cylinder. If I had ever had been challenged by another M14/M1a shooter for such I would ask how there G/C was unitized? If they replied there was screwed and glued I would then protest them right there on the spot. If there spindle valve don't turn, there rifle is altered just the same... Karma, funny how that works ain't it?
 
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