"Over Gassed" AR's Fact or Fiction? Other Perspectives
- Thread starter Flexible Tangerine Sprite
- Start date
For op to flex on us with all his experience but clearly be wrong in the end… some guns need gas adjustment end of story. Dude can flex all his military experience he wants but real world use tells a different story.
Sure guns spec’d with the correct port size for an appropriate application will not need any tuning. Others will definitely need tuning.
Didn't read the thread but will throw out my experience.
First off, I will concede that under-gassing or over-springing or over-weighting the buffer will cause more feed problems than over-gassing. You see this a lot in 3-gun and other comps where guys are trying to run the ragged edge and reduce recoil. That said, at some point, increasing the gas will 100% cause feeding, stove pipe, and ejection problems. Somewhere in the abyss I have high-speed footage that shows as much.
The lateral velocity of the ejecting case is pretty much constant and is determined by the ejector plunger spring and the ability of the extractor to properly keep hold of the case. As you increase gas, the rearward velocity component increases and the ejection angle changes, becoming more shallow. Eventually you start hitting the brass deflector (no big deal, still ejects 3:00-4:00), and then as you keep adding gas your cases smack the rear of the ejection port before they can clear the ejection port. This is when you start seeing 12:30-2:00 ejection. Keep adding gas and the cases will hit the rear of the ejection port then fly back into the upper. Sometimes you get extractor issues here, too, with the increased rearward velocity.
Bolt carrier velocity and the impulse of the BCG bottoming out causes a dynamic response to the rest of the system. Sometimes it's no big deal, sometimes, especially with sloppy magazine wells or lowers that hold the magazine at a lower height it definitely can cause feeding problems. The root issue is probably more the loosey goosey magazine well, but excessive recoil/gas isn't helping.
From an accuracy standpoint, I also have documented an increase in the frequency and the severity of fliers when increasing gas to the system.
I am firmly of the opinion that you want as little gas as is necessary to 100% function the system in the range of cleanliness/lube/temp/weather conditions you'll experience unless accuracy isn't on the priority list then gas it up to the point that you avoid the afore-mentioned function problems.
YMMV.
First off, I will concede that under-gassing or over-springing or over-weighting the buffer will cause more feed problems than over-gassing. You see this a lot in 3-gun and other comps where guys are trying to run the ragged edge and reduce recoil. That said, at some point, increasing the gas will 100% cause feeding, stove pipe, and ejection problems. Somewhere in the abyss I have high-speed footage that shows as much.
The lateral velocity of the ejecting case is pretty much constant and is determined by the ejector plunger spring and the ability of the extractor to properly keep hold of the case. As you increase gas, the rearward velocity component increases and the ejection angle changes, becoming more shallow. Eventually you start hitting the brass deflector (no big deal, still ejects 3:00-4:00), and then as you keep adding gas your cases smack the rear of the ejection port before they can clear the ejection port. This is when you start seeing 12:30-2:00 ejection. Keep adding gas and the cases will hit the rear of the ejection port then fly back into the upper. Sometimes you get extractor issues here, too, with the increased rearward velocity.
Bolt carrier velocity and the impulse of the BCG bottoming out causes a dynamic response to the rest of the system. Sometimes it's no big deal, sometimes, especially with sloppy magazine wells or lowers that hold the magazine at a lower height it definitely can cause feeding problems. The root issue is probably more the loosey goosey magazine well, but excessive recoil/gas isn't helping.
From an accuracy standpoint, I also have documented an increase in the frequency and the severity of fliers when increasing gas to the system.
I am firmly of the opinion that you want as little gas as is necessary to 100% function the system in the range of cleanliness/lube/temp/weather conditions you'll experience unless accuracy isn't on the priority list then gas it up to the point that you avoid the afore-mentioned function problems.
YMMV.
FWIW.... I worked on a CLGS 16", with a gas port size of over .100 ( biggest pin gauge I had. )..... guess what the problem was ?
The over sized gas port was breaking the hammer pin in half. The BCG was slamming it so hard !
The OEM one was broke in clear in half when I got it. I told the owner to get a proper gas ported barrel and I will replace it for him.
He and his buddies had all bought the same AR from the same local company... one by one, same issue 3X.
I agree with this. A vast majority of gassing problems are likely user induced. Too much buffer and/or too much spring.
For all of those guys out there that treat the AR platform as though they are playing with tinker toys, it's really handy to have a set of pin gauges. To say that you've assembled these parts and then post questions regarding which buffer and or spring to go with is almost like shooting in the dark (without NV). If you post those same questions with some information, like the size of your gas port, diagnosis would be a lot easier.
For common calibers, like 5.56, you can usually tell with a higher degree of certainty, what the proper buffer weight will be, if you know the gas port size.
I can confirm this, I've also seen high speed video of feeding issues on an over gassed system. Carrier velocities were way too high. When gas was reduced to bring carrier velocities into normal range, the feeding issues seen on HSV went away. No changes to action spring or buffer weights were made.
There is a Ukrobot here that goes by the handle of “LRRPF52” who constantly spews pro - Ukrainian propaganda and writes in the exact same bloviating style, always presuming to speak from a soapbox of moral and intellectual superiority.
A hallmark of this bot’s exposition style is the use of “I have yet to see.”
LRRPF52, is this you?
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I didn't know he was a big Ukraine guy, then again I rarely leave the semi auto subforum, but if you really want to ask him we can tag him.
@LRRPF52
I can make an AR FTF by both over and under gassing the system. I think the OP's next thread will be "The Sky Isn't Blue".
I assumed a different member who insists on over-gassing....but the tone and syntax is all wrong
"For the carpenter who's only tool is a hammer, all his solutions tend to look like Glocks"
(or something like that)
(or something like that)
I keep an open mind to learning new things so I keep waiting for the OP to say something profound, but I'm pretty sure he should sum up this tread and just come out and say that he's a dusty old curmudgeon that doesn't like all these new fangled AGB's and extended gas system lengths because "back in my day we didn't have all that stuff and we got along just fine!".
I figured: “I wanna run the spiciest of the spicy in 120 degree heat, suppressed…and when shtf, the crappiest steel cased puff load in Arctic conditions unsuppressed”
If it comes to it, I figure I can just throw a handful of Tula on the ground and the scavenger panic should be enough to allow for an escape...
My guess is Op isn't coming back with any real informative knowledge. I certainly don't claim to know it all by any means but even a smooth brain like myself, have remedied many an issue with an adjustable gas block or smaller id gas tube. That alone tells me that over gassing is real. Could something else contribute to the issue sure but if lower gas fixed it why waste anymore time or energy.
Reducing bolt failure issues is the reason to use AGB's as I understand it. Reduced recoil is an added bonus. Just about every problem with over-gassing relates to the bolt. Cam pins snapping, bolt lugs breaking early, excess fouling issues like stuck firing pins, stuck ejector plungers, carbon doughnut on bolt face screwing with headspace, etc. There's more benefits to using AGB's than not using them.
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