M&P Needs New Gas Rings @ 800 Rounds

[spitnine]

While cleaning the M&P Sport II, I noticed that the bolt was moving very freely although the rifle was still running fine.
Did the "stand me on my nose" BCG test and carrier fell right down.
Put in new rings and bolt tightened right up.
Thanks

 

[Rastoff]

I've never heard of the "stand me on my nose" test before. Interesting.

I wouldn't replace the rings until the gun malfunctions. None of mine have ever malfunctioned. I have a lot more rounds through mine than you do.

 

[spitnine]

I've never heard of the "stand me on my nose" test before. Interesting.
I wouldn't replace the rings until the gun malfunctions. None of mine have ever malfunctioned. I have a lot more rounds through mine than you do.

I haven't had any brand new ARs need rings that soon either.
The closest I have is a Ruger AR556 that needed new rings around 2,000 rounds.
I realize that most rifles will still run with well worn and even broken rings but prefer to change them since they are cheap and easy to change.
That said, this rifle ran (and continues to run) right out of the box without any issues at all.
Thanks

 

[zombie66]

M&P Needs New Gas Rings @ 800 Rounds

While cleaning the M&P Sport II, I noticed that the bolt was moving very freely although the rifle was still running fine.
Did the "stand me on my nose" BCG test and carrier fell right down.
Put in new rings and bolt tightened right up.
Thanks

Is this the test where you lock the bolt back and lightly tap the barrel on the ground to see if the bolt kicks forward?

 

[cyphertext]

This "test" is not reliable... Folks often point to the military, but this is not what is taught. The military manual states that you should hold the bolt carrier assembly where the bolt is facing downward and the bolt should not drop downward.

Basically, the bolt with the gas rings is like a piston. It should be tight enough to create a seal and hold it's own weight, but if you add weight (i.e. the weight of the bolt carrier pushing down), you can overcome the friction that is creating the seal.

If the gas rings can support the weight of the bolt and do not allow it to fall from the assembly, the rings are good. If it passes like this, yet fails to hold the weight of the bolt carrier as posted above, you are replacing perfectly good gas rings that have been broken in.

 

[spitnine]

Gas Rings

This "test" is not reliable... Folks often point to the military, but this is not what is taught. The military manual states that you should hold the bolt carrier assembly where the bolt is facing downward and the bolt should not drop downward.
Basically, the bolt with the gas rings is like a piston. It should be tight enough to create a seal and hold it's own weight, but if you add weight (i.e. the weight of the bolt carrier pushing down), you can overcome the friction that is creating the seal.
If the gas rings can support the weight of the bolt and do not allow it to fall from the assembly, the rings are good. If it passes like this, yet fails to hold the weight of the bolt carrier as posted above, you are replacing perfectly good gas rings that have been broken in.

I realize that most rifles will still run with well worn and even broken rings but prefer to change them since they are cheap and easy to change.
Thanks.

 

[cyphertext]

I realize that most rifles will still run with well worn and even broken rings but prefer to change them since they are cheap and easy to change.
Thanks.

Your rifle, your money... but note that your "test" does not indicate the rings need to be replaced.

 

[rtquig]

This is why I like this forum, the knowledgeable answers to questions. I had heard like the OP, to put the bolt on a table and if it slides down easily, then it is time to change the rings. The answers now make me question what I have been told. I don't know where I originally heard that method, but it was a gun forum.

 

[blues7]

This is why I like this forum, the knowledgeable answers to questions. I had heard like the OP, to put the bolt on a table and if it slides down easily, then it is time to change the rings. The answers now make me question what I have been told. I don't know where I originally heard that method, but it was a gun forum.

I've seen that advice given online via forum and video, as well as in writing.

I agree with you, the advice provided above seems both more practical and more realistic. (I'll certainly keep it in mind down the road.)

 

[noro]

Spitnine,

Your rifle - your choice. The gas rings are pretty cheap. If it makes you more comfortable, and your rifle is functioning fine, then go for it. I would think the gas rings would last more than 800 rounds.

I found out with my rifle, that most malfunctions in the gas system are usually found in the gas key or staking, not the rings. Its certainly wise though to be familiar with your rifle and take preventative measures should you think something is amiss. The parts are pretty cheap. Your confidence in the rifle, though is priceless.

 

[cyphertext]

We have all seen it out there... even some "experts" teach that method, and many state that they learned it in the military. I've been told that it is taught that way at the Colt armorer school.

Here is a link to the TM... There may be a newer one that supersedes this one. I just took the first hit from Google.

http://pdf.textfiles.com/manuals/MILITARY/Army%20M16A2%20and%20M4%20manual.pdf

The gas ring test is on page 43 of the PDF.

 

[WR Moore]

I double checked the USMC manual and retention of the bolt against gravity, less cam pin, is specified. I expect what we may see here is what you'd like to see (support carrier) vs what's absolutely necessary for reliable function (retain bolt).

All gas rings are probably sourced from a limited number of sources and the occasional batch that has less than stellar service life probably happens.

Gas rings are cheap.

 

[spitnine]

My Original Point

Spitnine,
Your rifle - your choice. The gas rings are pretty cheap. If it makes you more comfortable, and your rifle is functioning fine, then go for it. I would think the gas rings would last more than 800 rounds.

I found out with my rifle, that most malfunctions in the gas system are usually found in the gas key or staking, not the rings. Its certainly wise though to be familiar with your rifle and take preventative measures should you think something is amiss. The parts are pretty cheap. Your confidence in the rifle, though is priceless.

My original post was just noting that this is the first of my rifles that had the gas rings wear to that point (my test) so quickly.
The nearest was the AR556 at 2,000 rounds.
I have been fortunate enough to have never had a gas key or a gas key screw come loose though.
The cited FM does use the bolt falling out of the carrier test but I have never run a rifle that far before changing the rings.
Thanks.

 

[hdwhit]

spitnine wrote:
Did the "stand me on my nose" BCG test...

You have not answered the question about what the "stand me on my nose" test consists of and where you got it from.

 

[blues7]

You have not answered the question about what the "stand me on my nose" test consists of and where you got it from.

You didn't ask me but as I recall, you simply extend the bolt from the carrier, (as you would do before reassembling the rifle), and stand the BCG vertically on the bolt end .

If the bolt slides back into the carrier under the weight of the assembly, the theory was that the gas rings needed changing as the seal was not tight enough.

 

[Maddmax]

You didn't ask me but as I recall, you simply extend the bolt from the carrier, (as you would do before reassembling the rifle), and stand the BCG vertically on the bolt end .

If the bolt slides back into the carrier under the weight of the assembly, the theory was that the gas rings needed changing as the seal was not tight enough.

...Or, you just needed to re-adjust your rings because they have lined up. Rare, but can happen now and then.

 

[Rastoff]

...Or, you just needed to re-adjust your rings because they have lined up. Rare, but can happen now and then.

No, this is not the same. The test described is testing the friction of the rings. Whether the gaps (I assume that's what you mean) are lined up or not will not change the amount of friction the put on the carrier.


Even so, I'm not convinced this "test" has any validity. If the gun is working, i.e. completely cycling when fired without causing a malfunction, then the rings are fine. At least that makes sense to me. I guess this test could be an indicator of wear and allow them to be changes prior to failure. I just don't see the point. I have over 3K rounds through one gun and it still works as advertised.

 

[Maddmax]

No, this is not the same. The test described is testing the friction of the rings. Whether the gaps (I assume that's what you mean) are lined up or not will not change the amount of friction the put on the carrier.


Even so, I'm not convinced this "test" has any validity. If the gun is working, i.e. completely cycling when fired without causing a malfunction, then the rings are fine. At least that makes sense to me. I guess this test could be an indicator of wear and allow them to be changes prior to failure. I just don't see the point. I have over 3K rounds through one gun and it still works as advertised.

There are a lot of variables involved here. First, the shooter only has 4 posts. We both know those Sport II's with carbine length gas systems are way over gassed. What kind of lube and a how well was the weapon really maintained. Ammo ? ("likely" dirty & cheap). How many mag dumps.

About the time you think you've seen it all something off the wall pops up out of nowhere. I've had my share of raised eyebrow moments over the years with "greenhorns" new to the hobby/sport.

New rings after 800 rounds. ….ok ???.. That's a new one, interesting... Nothing I'm going to loose any sleep over... All mine function just fine.

 

[spitnine]

If I May...

Lube on all of them is original O-158.
Really maintained is thoroughly cleaned after every range trip. Usually 100 to 200 rounds, twice a week.
Ammo is PPU, Wolf Gold, Federal, Geco, Norma, IMI.
I don't do steel.
I also don't do mag dumps as I consider them a frivolous waste of ammo.
FWIW, I have well over 20,000 rounds through various ARs, my SP1 is just shy of 10,000.
I bought the Sport II just to compare it to a couple of other major firearms manufacturers ARs.
BTW, it runs great. I like it and recommend it as an excellent starter AR. The only out-of-the-box issue was the spring clip on the dust cover hinge was not installed in its groove and fell off. I put one of my spares on and all was good.
Thanks

 

[Maddmax]

Lube on all of them is original O-158.
Really maintained is thoroughly cleaned after every range trip. Usually 100 to 200 rounds, twice a week.
Ammo is PPU, Wolf Gold, Federal, Geco, Norma, IMI.
I don't do steel.
I also don't do mag dumps as I consider them a frivolous waste of ammo.
FWIW, I have well over 20,000 rounds through various ARs, my SP1 is just shy of 10,000.
I bought the Sport II just to compare it to a couple of other major firearms manufacturers ARs.
BTW, it runs great. I like it and recommend it as an excellent starter AR. The only out-of-the-box issue was the spring clip on the dust cover hinge was not installed in its groove and fell off. I put one of my spares on and all was good.
Thanks

Sounds like you're doing everything right. Might double check your bolt and check out the machining work from the factory. It should be nice and smooth. "Could" have missed a step in machining and it wasn't sized to speck ?? Could just be a fluke, but something wore those rings down if they only lasted 800 rounds and it wouldn't hurt keeping a close eye on them. Keep us updated if it persists.