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SIG 516 and 716 - Gas Port Positions

37K views 25 replies 10 participants last post by  Edsel 
#1 · (Edited)
Some inconsistencies in layout I noticed here.

SIG 516 Gen 2: I assume the Medium Dot is the normal position; the tab (with the big hole through it) is aligned with the Medium Dot, and is vertical when using this setting.

X - Big Dot - Medium Dot - Small Dot

SIG 716 Gen 2: I'm not sure which one is the normal position; the tab is aligned with the Small Dot, and is vertical when using this setting.

X - Small Dot - Medium Dot - Big Dot

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I'm assuming that for both rifles, the X is for total cut - off, the Small Dot is for Suppressors, the Medium Dot is for Regular Use, and the Big Dot is for Adverse Conditions.

Could anyone confirm this?

What I don't get is why the tab isn't vertically arranged with the Medium Dot on the SIG 716.
 
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#3 · (Edited)
#4 · (Edited)
The question is, does it follow that for both rifles, the X is for total cut - off, the Small Dot is for Suppressors, the Medium Dot is for Regular Use, and the Big Dot is for Adverse Conditions?

And why isn't the tab vertically aligned with the Medium Dot on the SIG 716?
 
#6 ·
I have a new 516 FDE as well and was confused as to which setting was what, my manual must be the old one also. I did go shoot my gun however and the Large dot seem to cycle the best so I figured that was the adverse setting. The other two settings did not cycle at all they were both behaving as a single shot. Also on every setting the bolt would never stay open after the last round was fired from the magazine, curious to know if anyone has experienced the same?
 
#8 ·
I will receive my 556-762R this week and I will compare. So many discussions about the Gas Valve positions, I just don't get it. I have never rotated (changed position) my Gas Valve from the position it was when I opened the box. I would think that Sig intentionally designed the Gas Valve with the rotation knob to be vertical for normal operation. If the Gas Valve requires positioning of the largest port hole to be aligned with the barrel's port hole for the weapon to function normally, we are missing something. On my 716, I contribute (convinced) the three failure to fully extract was due to the buffer assembly and tube were packed with preservative grease. After I cleaned all buffer components and the inside of the buffer tube, I never had any issues.
 
#9 · (Edited)
Default positions of Gas Ports from factory.

I've been running with these settings ever since I got my rifles, no issues.

Notice that both tabs are oriented vertically relative to the barrel.

SIG 516

No issues here - everything's still intuitive; Small Dot for Suppressors, Medium Dot for Regular Use, Large Dot for Adverse Conditions. I have tested the Small Dot for Regular Use - the bolt wouldn't cycle properly.

The "ears" on each side of the plug are level.

X - Big Dot - Medium Dot - Small Dot



SIG 716

This is what throws me off; notice how the tab is oriented vertically relative to the barrel, but the "ears" are lopsided - with the one on the side of the X being higher. The default position appears to be the Small Dot - how does one run the rifle suppressed? Thus far I'm not having any cycling / extraction / last round hold - open issues.

X - Small Dot - Medium Dot - Big Dot



Haven't really asked SIG about any of this yet - since the rifles are running fine.
 

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#10 ·
Figured it out.

Embarassing, sort of.

The manual for the SIG 516 doesn't seem to have been updated and still has the issues mentioned in the earlier post. The manual for the SIG 716 seems all right.

The Gas Port "Locator Points" are different for each rifle.

On the SIG 516, settings (or "dots") are indicated by a vertical line on the Gas Block (highlighted in red).

The SIG 716, on the other hand, uses a large circle towards the side of the Gas Block (highlighted in yellow).

 

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#11 ·
It seems that my SIG 716 was set on the Medium Dot, after all.

 

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#12 ·
I was going to say, mine is on normal operation when it's straight up & page 80 of my manual shows the correlation of the dots. Glad you got it figured out.
 
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#13 ·
What was misleading was the 516's inconsistent manual and slightly different layout of the gas block + valve positions on the 716.
 
#14 ·
Question, my 516, first sig ever for me so cut me some slake,
The gas port does not have dots at all, no lines, etc. it has detents and pin. One detent keeps knob vertical, same detent let's knob move 1 click. Then pin must be pushed in to move knob about quarter turn to next detent. Last detent, push pin and turn knob about 90 degrees. All counter clockwise facing the muzzle, by the way mine did not have manual with it. What is the positions for suppressed and adverse.
 
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#16 ·
Sounds like a great idea, sorry for the late reply...
 
#17 ·
Had the same problem with my 516 not cycling on medium dot setting using 45 grain rounds (had to manually cycle each time...not good). Will try again tomorrow on large dot setting and 55 grain...and will test medium dot at 62 grain. The gas valve positions on my user's manual (Rev 07, booklet) didn't match my rifle, but found a Rev 05 manual (PDF) online that seems to match.

Small dot = Suppressed = "Position #3" in manual = 1st position on my rifle (11:00)
Medium dot = Normal = "Position #1" in manual = 2nd position on my rifle (12:00)
Large dot = Adverse = "Position #2" in manual = 3rd position on my rifle (1:00)
X mark = Off = "Position #4" in manual = 4th position on my rifle (2:00)
(manual = Rev 05)
 
#18 ·
The SIG Gen 2 gas port design is probably one of the rifle's highlights.

Doesn't foul easily with carbon or copper, and ef it does - easy to disassemble, easy to clean.
 
#20 ·
I tried 55 grain rounds today on Normal but had to switch to Adverse setting after it failed to cycle. After a few rounds I switched back to Normal and had no problems since. I brought 62 grain rounds also, but the indoor range I went to doesn't allow it. My 516 is about a week old and I've used it twice now.
 
#22 ·
I've got another question for you 516 owners.

When moving the gas valve from the normal to adverse setting, mine is tight but still fairly easy to twist, without pushing in the detent pin. On the other two settings, you must push in the detent, and it is still pretty tight and difficult to twist. I will say, that is with the gun a bit dirty, like end of a range session. After cleaning and lubricating, it is significantly easier to turn.

What is your experience with your rifle?
 
#24 ·
Use a spent round to twist the selector.

It fits nicely in the hole.
 
#26 ·
I'm not sure...

It probably is :)
 
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