Who can help with my AR-15 problem?

Claven2 said:
For the bolt, once you get it out, check that the ejector is springy. Ensure the extractor moves. It might or might not have crane o-ring under the extractor, but even if it does not, I doubt this would give you the symptoms you are seeing. If it does have one though, it wouldn't hurt to install one (you have to drive the extractor pin out to do this).

Ensure the gas seal rings do not have holes lined up. Even if they are, the bolt will usually still work OK, but good practise to space them apart.

Now blow on the hole in the gas key to verify it is not obstructed.

If all those things ckeck out, re-assemble the bolt carrier group as it's likely OK.

Before shooting, lube the living crap out of the sides of the gas key, the cam pin and the bearing rails on the bolt carrier. In my experience, many (most?) Ar15 failures are related to insufficient lubrication.

Use a good runny gun oil like Hoppes, Remoil, CLP, etc.
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The idea of the gas ring gaps having to be lined up is total BS and unicorn-like in it's mythicalness. I have fired AR's and full-auto C7/C8's with 1 (one) gas ring and none of them ever failed to work.

My 14.5" mid-length has never seen oil at all only Motomaster Wheel Bearing and Axle grease and now has somewhere north of 12K thru it without a single stoppage so the idea of "only good runny oil" has been proven fallacious and by others far more qualified than I.

As to the OP's problem, I would suggest getting your hands on a good AR15 manual and getting familiar with the workings of the rifle before you go suggesting that you're thinking of tearing down the BCG and removing the gas key. The system isn't difficult to work on but it seems that everyone with an AR15 instantaneously becomes an armourer. Next thing you know we'll be seeing posts about how Brand X is a piece of crap and doesn't work properly but most (if any) will never mention that they buggered with it since day 1...


blake
 
mudgunner49 said:
The idea of the gas ring gaps having to be lined up is total BS and unicorn-like in it's mythicalness. I have fired AR's and full-auto C7/C8's with 1 (one) gas ring and none of them ever failed to work.

My 14.5" mid-length has never seen oil at all only Motomaster Wheel Bearing and Axle grease and now has somewhere north of 12K thru it without a single stoppage so the idea of "only good runny oil" has been proven fallacious and by others far more qualified than I.

As to the OP's problem, I would suggest getting your hands on a good AR15 manual and getting familiar with the workings of the rifle before you go suggesting that you're thinking of tearing down the BCG and removing the gas key. The system isn't difficult to work on but it seems that everyone with an AR15 instantaneously becomes an armourer. Next thing you know we'll be seeing posts about how Brand X is a piece of crap and doesn't work properly but most (if any) will never mention that they buggered with it since day 1...


blake
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Blake,

A properly tuned and broken-in AR will run with only one gas ring and any lube you want to use.

I merely want the OP to try the obvious things according to good practise. If he gets his gun working well, he can try non-issue lubes and other interesting things.
 
Claven2 said:
Blake,

A properly tuned and broken-in AR will run with only one gas ring and any lube you want to use.

I merely want the OP to try the obvious things according to good practise. If he gets his gun working well, he can try non-issue lubes and other interesting things.
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Tuned and broken-in nothing - I've done it with new out of the box rifles and no issue. It's still bad data. There is much of it on this site from folks who don't know what they don't know (from the Four Levels of Competence).

I think everybody who buys an AR should have to read the manual before they start going all "Lego-maniac" on their new toy, if even so they at least learn proper terminology.

I'm not sure exactly what you mean by "non-issue lubes and other interesting things", maybe I'm reading too much into it...
 
The OP can spend all the time inthe world screwing with the bolt and the gas system and other things but it is all a waste of time cause the problem is in the chamber. Nothing in the bolt, buffer, recoil spring or gas system would cause the extractor to rip the case rim off. That is the result of the case sticking in the chamber.
 
It sounds to me like a very tight chamber, one not cut deep enough perhaps. Chamber a round and pull it out, check to see if the rifleing had touched the bullet at all.

Scott
 
Suputin said:
The OP can spend all the time inthe world screwing with the bolt and the gas system and other things but it is all a waste of time cause the problem is in the chamber. Nothing in the bolt, buffer, recoil spring or gas system would cause the extractor to rip the case rim off. That is the result of the case sticking in the chamber.
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


This
 
mudgunner49 said:
Tuned and broken-in nothing - I've done it with new out of the box rifles and no issue. It's still bad data. There is much of it on this site from folks who don't know what they don't know (from the Four Levels of Competence).

I think everybody who buys an AR should have to read the manual before they start going all "Lego-maniac" on their new toy, if even so they at least learn proper terminology.

I'm not sure exactly what you mean by "non-issue lubes and other interesting things", maybe I'm reading too much into it...
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I mean that the M16 manual of arms doesn't have grease anywhere in it. It specifies Break-free CLP and for trouble-shooting that is what he should be using. (or something very like it)

Your "luck" with out of the box rifles is irrelevant. The fact is his rifle does not work and he needs to test it in optimal configuration.
 
Suputin said:
The OP can spend all the time inthe world screwing with the bolt and the gas system and other things but it is all a waste of time cause the problem is in the chamber. Nothing in the bolt, buffer, recoil spring or gas system would cause the extractor to rip the case rim off. That is the result of the case sticking in the chamber.
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I generally agree with you, but the OP says his chamber is clean and smooth. I've shot AR's with VERY poorly reamed chambers before - lots of deep circular machining marks in them, burrs, etc. Even then, the rounds only stuck with steel cased ammo and not every round did so.

Using a Crane o-ring decreases the effects of a flawed chamber (not a fix, mind you...)

Also, I find steel cased ammo is far more likely to have the rim break off on extraction than the more elastic brass cases.

It is likely chamber related, but it would have to be pretty bad to do it on every shot - unless he also has an over-gassing issue compounding the problem.
 
Claven2 said:
I mean that the M16 manual of arms doesn't have grease anywhere in it. It specifies Break-free CLP and for trouble-shooting that is what he should be using. (or something very like it)

Your "luck" with out of the box rifles is irrelevant. The fact is his rifle does not work and he needs to test it in optimal configuration.
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It is not "luck" with out of the box rifles - I'm talking dozens if not hundreds of service rifles in several configurations - and I truly doubt that it is irrelevant. I understand the gist of what you're trying to say, but FWIW the M16 manual of arms was written in the 1960's and we've learned a LOT since then. Lubes, PM, things that work and don't work, shooting stance, RDS, IA drills - the list goes on.

I'm with Suputin on this one - I'm going to say chamber related, more specifically an under-sized chamber (since it's not visibly rough). I't very rare that an AR would be so much over-gassed (a term that lots fo folks use but few understand - kind of like "DNA") as to be ripping rims off. I suppose the gas port could be drasically over-sized but I still lean toward the chamber being the problem...


blake
 
I don't disagree - it would be strange though to see an undersized chamber on a S&W Ar15. While not top tier, their QA/Qc is generally good.
 
thanx you guys for all your help, this one has had me baffled as well, i have taked evreything apart, and all looks good, i stuck a snapcap in their to cycle it threw, now the charging handle wont pull back, its completley jamed, i have tryed roding it and pulling down to no avail, fed up i have contacted the place i bought the rifle, when mine was orderd they also brought in a few more to sell, when i explained the problems they checked the other Ar's and found that the chambers were machiened a little smaller than they should be, and they are all numbers within 10 digets of mine, likely an assembley line mishap, little disapointed thinking i was getting a good quality AR, so many to choose from., i am taking the gun in tomorrow and they will likley send mine and the others back to S&W, i will keep you guys posted on what i find out, again...., i realy appreciate all your feed back and responces, you guys have bin very very helpfull, i hope you all have a great holiday season and i will post again soon, thank you...
 
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