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Nm gas cylinder marking

2K views 20 replies 10 participants last post by  Ted Brown 
#1 ·
How can you tell a gc is nm? I understand it will be unitized by weld, but other than that, any visible markings i can verify? Thanks.
 
#2 ·
The Gas System are two clear ways.

#1, Drill, tap, screws and glue.

#2, As you noted above, welded.

DI5
 
#6 ·
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.
 
#10 ·
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.
 
#12 ·
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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#20 ·
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?
 
#17 ·
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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