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/fl...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.