gas rings?

[cz777]

after total of 350 rds fired the gas rings fail the ring test -new ar was lubed and all rest p/m before this . would work lapping of bolt carrier be part of this ? what makes the gas rings fail ? rough finish? carbon build up-new weapon? ? carbine gas system over compress the rings?

[Quib]

Check the inner surface of the bolt carrier for rough spots.

Purchase a set of rings from a known source for quality parts. Bravo Company is one of those sources.

Keep the rings well lubed.

[rebelEMPIRE]

I don't understand the nature of your "failure".

But the best advice I can give with regards to your gas rings is to make sure the slits are staggered when inspecting your bolt as opposed to stacked or aligned. This allows the rings to seal gas pressure effectively. And of course as stated above, lubricate them.

That aside, without a detailed description or picture of your gas rings, it would be difficult to diagnose. A picture of the inside of your BCG bore would also help.

-rebelEMPIRE

-

[Gator]

I think he meant the gas ring test where you let it stand on the bolt face to see if it closes on itself.
I too have a question on the test... Quib, should it not close even when heavily lubed?

[Quib]

The staggering of the gas rings before reassembly has been preached and practiced for years. But in reality it doesn’t affect the functioning of the weapon.

First off, the ring gaps are compressed during insertion into the bolt, reducing the gap. Second, the rings migrate around the bolt during firing, and often times the gaps align purely on their own.

I personally haven’t tried it, but there are those who report running the weapon on less than three rings. The three rings are there for redundancy. If one fails, you still have two. If two fail, you still have one.

[Quib]

I too have a question on the test... Quib, should it not close even when heavily lubed?

The test is performed with a clean, dry bolt. The TM specifically states this.

ETA: The military -23&P, and the Colt Maintenance Manual, both have the gas ring test performed holding the bolt carrier suspended verses standing the bolt and carrier upright on a table top.

I could be wrong, but personally I think that the “table top” procedure came about by people misinterpreting the manual.

I personally have yet to see the “table top” procedure documented in any maintenance manuals to date. I did recently discussed this with a person in the industry who stated the same, but noted that the “table top method” is often taught in armorers courses.

[Eric]

I personally haven’t tried it, but there are those who report running the weapon on less than three rings. In the Colt Armorer Classes we discuss this. Being a skeptic, I had to try it for myself. My particular test weapon ran fine with 3, 2 and 1 gas ring. Obviously nobody is recommending running it with anything less than three good rings, but it was interesting.

[Quib]

In the Colt Armorer Classes we discuss this. Being a skeptic, I had to try it for myself. My particular test weapon ran fine with 3, 2 and 1 gas ring. Obviously nobody is recommending running it with anything less than three good rings, but it was interesting.

Thanks for the input Eric. I may try this for myself next time out.

[cz777]

Check the inner surface of the bolt carrier for rough spots.

Purchase a set of rings from a known source for quality parts. Bravo Company is one of those sources.

Keep the rings well lubed.


bolt carrier is ok and its young manufacturing --same source clp is used like i was taught in the army .....thxs

[alt154shiver]

In the Colt Armorer Classes we discuss this. Being a skeptic, I had to try it for myself. My particular test weapon ran fine with 3, 2 and 1 gas ring. Obviously nobody is recommending running it with anything less than three good rings, but it was interesting.

Call this a n00b question, but what exactly do the gas rings do? I'm picturing the cycle of operations in my head and the only thing I can come up with is that they stabilize the bolt in the carrier and provide (what I'm assuming) is some sort of necessary resistance as the weapon cycles.

Is there something I'm missing?

[Quib]

The gas rings create a seal, forming one wall of the chamber mentioned below in this excerpt from FM23-9.

d. Firing

With a round in the chamber, the hammer cocked, and the selector on SEMI, the firer squeezes the trigger. The trigger rotates on the trigger pin, depressing the nose of the trigger, and disengaging the notch on the bottom of the hammer. The hammer spring drives the hammer forward. The hammer strikes the head of the firing pin, driving the firing pin through the bolt into the primer of the round. When the primer is struck by the firing pin, it ignites and causes the powder in the cartridge to ignite. The gas generated by the rapid burning of the powder forces the projectile from the cartridge and propels it through the barrel. After the projectile has passed the gas port (located on the upper surface of the barrel under the front sight, and before it leaves the barrel, some gas enters the gas port and moves into the gas tube. The gas tube directs the gas into the bolt carrier. It passes through the key downward into a space between the rear of the carrier’s bolt cavity and the rear of the bolt itself. The gas then expands. The bolt is locked into the barrel extension and unable to move forward, and the carrier is thus forced to the
rear by the expanding gas.

If the rings were not present, the gas would never build pressure, and simply escape between the bolt and carrier.

[federalist22]

I posted this last night in another thread and thought it might be useful here, although it does not show all detail inside the bolt carrier, it does show the cycling operation. The Army Times posted this back in 2007 around the time the HK416 vs M4 debate got hot in Congress with Sen. Coburn. I kept the link because it depicts the action of DI and piston systems in a pretty simplistic manner. This animation was designed to show how the Colt M4 and the HK416 operate. To view the other weapon, click the "compare to..HK416 or M4" button inside the animation above the 2007 Copyright mark. More or less, this describes what is happening during the cycling of your rifle, regardless of DI or the various pistons on the market.

Here's the link: http://www.armytimes.com/projects/flash/2007_02_20_carbine/.

This link requires that you have a Flash Player installed.

[alt154shiver]

I was unaware that a channel existed from the key into the bolt carrier. The dawn of realization...

I was always under the impression that the gas pushed directly on the gas key. Which is probably why I never really got the carrier tilt argument against piston guns.

But it now all makes sense. Thank you gentlemen.

[Quib]

That Army Times animation is not bad, but it doesn’t go into any detail once the gas gets to the Carrier Key.

That animation leads folks to believe, as alt154shiver once did before reading this post, that the gas path ended upon entering the key.

[Quib]

......it now all makes sense. Thank you gentlemen.

You’re welcome.

I’m glad to hear this thread made things clearer. After all, this is what it’s all about. [:)]

[Blankwaffe]

I had a similar issue with some Armalite gas rings awhile back that had a service life below 500 rounds.In my opinion they were made with a soft material and very jagged edges.Both of which allowed the rings to wear at an increasing rate and they collapsed losing tension.The ends of the gas rings were slash cut like // rather than the typical tear drop shape.I personally suspected them to be import parts as the gas key screws on the BCG's were YFS import as well.I made the switch to using the dreaded McFarland rings and have not had any issues since.

I use the gas ring test that is done by standing the BCG bolt face down myself.Honestly I can't remember where I picked it up,but Ive been doing it well before I had a computer or internet(twenty years roughly),much less gun forum reading.
I was either shown by some ex-military folks(namely my uncles,Vietnam era vets) or it may have been the department armorer(also a Vietnam vet) when I was working as a LEO.So its been floating around for awhile.Ive asked several times over the years on the other site how the gas ring test should be done and you get both procedures in about a 50/50 mix of replies.So I don't know if one is best,right or wrong.But they both really have the same end result.
I like the table top procedure because in my opinion its an early predictor of gas ring wear.Probably a bit excessive but I do it.

[Quib]

I like the table top procedure because in my opinion its an early predictor of gas ring wear. Probably a bit excessive but I do it.

If anything, the “table top” method will have you replacing rings a bit earlier than the -23 method, simply because the carrier is heavier than the bolt.

[Captains1911]

I've found this interactive animation to be very helpful, found on Bushmaster website:

http://www.bushmaster.com/anatomy_bushmaster.asp

[Quib]

I've found this interactive animation to be very helpful, found on Bushmaster website:

http://www.bushmaster.com/anatomy_bushmaster.asp

That BM animation is pretty good. At least it shows the gas passage through the carrier key, and into the cavity mentioned above in my FM23-9 excerpt.

In the screen capture below, I highlighted the bolt ring position in yellow. Just to the rear of the rings, on the bolt tail, is the cavity. This is the area of the bolt that carbon builds up on.

http://img.photobucket.com/albums/v489/Metroliner/GasPathBM.png

[alt154shiver]

I've found this interactive animation to be very helpful, found on Bushmaster website:

http://www.bushmaster.com/anatomy_bushmaster.asp


Thanks you sir! I came across that animation a long time ago but lost the link. It is really good. Especially for teaching the cycle of operations.

[cz777]

[QUOTE=Blankwaffe;14349]says this and why '' the dreaded McFarland rings '' are they good or not?? well the carbine i was shotting on saturday didnt short cycle at tall with ''bad '' rings -i think the fouling help run her along ???

[Eric]

I have a couple ARs that are equipped with the McFarland gas rings and have not experienced any problems with them. New ones typically fit rather tight and I would suggest running them with heavy lube at first. I can't say that they are better than a decent new set of 3 standard gas rings though. Cost is under $4.

I too had one AR that ate a set of rings in less than 500 rounds, for no apparent reason. Malfunctions had not started, but they failed the check and were replaced. I think that worn gas rings are more likely to create a function problem when the system is already stressed from other issues like the weapon being dirty, dry, hot, etc.

[Quib]

I think that worn gas rings are more likely to create a function problem when the system is already stressed from other issues like the weapon being dirty, dry, hot, etc.

That’s my whole take on ring gap alignment as well.

In a clean, well maintained weapon, gap alignment should be a non-issue.

Start tossing in other variables such as,

- lack of lube
- extremely dirty weapon
- partially blocked gas path
- worn rings

Add in some of those variables, then you might be set up for a failure. And even then, I think we are talking in each case, the very extremes. Will the average AR owner see these extreme conditions? I personally don’t think so.

[federalist22]

Quib,

Well put on rings. I second your sentiment. Knowing that I take care of my weapon (clean, lube, and inspect when cleaning), rings are just not something I worry about.

[Blankwaffe]

If anything, the “table top” method will have you replacing rings a bit earlier than the -23 method, simply because the carrier is heavier than the bolt.

Yeap,thats what I meant to say and why I do it.

[Blankwaffe]

[QUOTE=Blankwaffe;14349]says this and why '' the dreaded McFarland rings '' are they good or not?? well the carbine i was shotting on saturday didnt short cycle at tall with ''bad '' rings -i think the fouling help run her along ???

I was trying to be sarcastic with the "dreaded McFarland gas ring" comment,sorry for the confusion.Alot of folks do not like the one piece McFarland ring and say they cause issues due to fit,tolerance etc..
That said Ive had excellent results with the McFarland rings my weapons with no related function issues.Once the ring is broken in they seem to not wear very much at all,so they are at least durable.

[spence.smith]

In the 30 years following the Vietnam War, the Army existed mainly as a peacetime force. The 1991 Gulf War was an armor-dominated fight, lasting only 100 hours. Most soldiers put their rifles to little or no use. But after Sept. 11, 2001, soldiers found themselves fighting protracted shooting wars in the harshest regions on the planet.
M16 rifles and newer M4 carbines no longer were stored in clean arms room racks. They were now a soldier?s constant companion, exposed to the super-fine dust and sand that blow across the desert landscapes of Afghanistan and Iraq. Still, the Army is quick to blame most M16 family malfunctions on soldiers not cleaning weapons properly.
So why then is it so wrong to pursue a more reliable assault rifle that holds up better (reliability) under the extreme conditions we're engaged in now?
Is it so wrong to admit maybe from time to time we do need to adopt new methods, patterns, tactics, and equipment?

[spence.smith]

Perfect Advice - I didn't know that one-piece gas rings were available - new to the AR-15, wanted to add one to the collection - mostly an AK-47 guy, but each has its place.

I've ordered the DPMS one-piece gas ring and I'll let you know how it works out.

After I get everything debugged I'll write up a summary of my build experience - including the name of the kit supplier.

The reason I wanted to build, instead of purchasing a completed weapon, is that I want to learn how to tweak and debug the AR platform. Also, given that I purchased the cheapest kit on the market, I fully expected to spend some time "dialing it in".

Throughout the shopping process and purchase the supplier has been extremely easy to work with. Did not contact the supplier about the bent gas ring because I suspected they'd just have me send the entire upper back which would deprive me of the learning experience.

[david.carroll01]

Perfect Advice - I didn't know that one-piece gas rings were available - new to the AR-15, wanted to add one to the collection - mostly an AK-47 guy, but each has its place.I've ordered the DPMS one-piece gas ring and I'll let you know how it works out.After I get everything debugged I'll write up a summary of my build experience - including the name of the kit supplier.The reason I wanted to build, instead of purchasing a completed weapon, is that I want to learn how to tweak and debug the AR platform. Also, given that I purchased the cheapest kit on the market, I fully expected to spend some time "dialing it in".Throughout the shopping process and purchase the supplier has been extremely easy to work with. Did not contact the supplier about the bent gas ring because I suspected they'd just have me send the entire upper back which would deprive me of the learning experience.

[Specialized Armament]

The 3 ring system allows each ring to independently conform to the bore of the bolt carrier, the one piece ring cant due to its design. I'd be willing to bet that one piece ring will wear out faster than a 3 ring set.