AR-15 extractor repeated extractor failure

[d2wing]

2 years ago I bought a built ar-15 at a gun show that seemed almost like new. It has a DPMS lower but no markings on barrel or upper parts. After about 20 rounds it started failing to eject. I took it to reputable gunsmith
who said the extractor was bad and replaced it. A week ago it did it agin several times. I found out it is common on the carbine length gas system and I need an extractor spring up grade. I decided to order a new BCM bolt from
Bravo country and I installed it today. Works like a charm. But, am I going to have a recurrance? I also bought a Les Baer extractor and a new spring for the old bolt and some #60 o-rings. The new bolt came with with a Crane o-ring and it looks just like the #60 o-ring btw.
My question is should I upgrade the buffer? It's not marked so I guess it's a standard carbine weight. From what I understand, with a 16' carbine, an H2
buffer would be the way to go but would like advice from yuz guyz.
If I had it to do over I'd buy a factory rifle so I knew what I had and had a warranty. Also I think I would go rifle length.

 

[TonyAngel]

Extractors and springs are routine maintenance items. I'm sure the Les Baer extractor is nice, but how much did it cost? The BCM upgrade kits are a good idea. I keep several in my box for when I need them. With the BCM kits, I've never had to use the insert. Just the spring does fine. When the spring gets weak, I just replace it. It's always a good idea to keep a spare extractor around too.

As for the insert (o-ring), I don't know that I'd just stick any hardware store o-ring in there. I don't know what the o-rings that BCM has are made of, but I have seen plain old hardware store o-rings swell when they absorb things like petroleum based lubricants.

As for needing a heavy buffer, it depends. How many rounds has the rifle seen? Have you changed the buffer spring to see if it makes a difference? Buffer springs are a regular maintenance item too, as are the gas rings. Using a known good extractor/spring with a fresh buffer spring, take note of your ejection pattern. Something between 3:00 and 4:30 is a good ejection pattern. If your ejection pattern is between 1:00 and 3:00, you may benefit from a heavier buffer. I like the ST-T2 buffers from Spike's.

 

[DBR]

The BCM extractor spring upgrade kit is what you need. It has the spring, insert and "O" ring. The "O" rings are not hardware store variety. They are made from a material called "viton". It is much more heat and chemical resistant than common neoprene rings.

Some after market extractor springs have five coils vs the original design four coils. The five coil springs can coil bind in some bolts and restrict extractor travel.

 

[Bartholomew Roberts]

I decided to order a new BCM bolt from Bravo country and I installed it today. Works like a charm. But, am I going to have a recurrance?

Springs are wear items and will eventually require replacement; but the minimum I would expect out of a good quality extractor spring is 3,000 rounds.

My question is should I upgrade the buffer? It's not marked so I guess it's a standard carbine weight.

There is no way of knowing with a parts gun. Parts guns can have all kinds of funky parts - buffers that don't weigh the correct amount, buffers that weigh the correct amount but are built differently. Improperly marked parts, etc.

Looking at where it ejects (as TonyAngel described above) is a good way to get an rough idea of whether your rifle could use a heavier buffer spring or buffer.

From what I understand, with a 16' carbine, an H2
buffer would be the way to go but would like advice from yuz guyz.

My basic rule is that if it is working for you and isn't broken, don't fix it. Many "reliability upgrades" for the AR can actually be downgrades if you don't have a good handle on how they work in the entire system - and with a parts gun that could have weird chamber sizing, different gas port sizing, gas port erosion or any other number of issues, that will be hard to do. However, if you do want to experiment with it...

Mike Pannone recommends a Sprinco Super-Duty M4 buffer spring and DPMS Extra-Heavy Buffer for carbine-length gas systems and he seems to have good luck with that combination on a standard M4. The DPMS buffer is 0.2oz lighter than an H3 buffer. On a parts gun, you may need to experiment a bit and what works for him may not work as well for you. An H2 buffer is probably a good, conservative place to start and I'd replace the action spring (also called the buffer spring) with a known good spring from a known manufacturer as well.

 

[Kwanger]

Mike Pannone recommends a Sprinco Super-Duty M4 buffer spring and DPMS Extra-Heavy Buffer for carbine-length gas systems and he seems to have good luck with that combination on a standard M4. The DPMS buffer is 0.2oz lighter than an H3 buffer. On a parts gun, you may need to experiment a bit and what works for him may not work as well for you. An H2 buffer is probably a good, conservative place to start and I'd replace the action spring (also called the buffer spring) with a known good spring from a known manufacturer as well.

I run a very similar setup in my Smith and Wesson M&P15T - the same Sprinco (Red) buffer spring, but with the Spikes ST-T2 Buffer (tiny bit lighter than a H2 buffer). There is a huge difference over stock - so much smoother. Have had no reliability/cycling issues whatsoever. One thing to mention about the Sprinco spring.....they have a bundle where you can get the extra power spring plus a new heavy duty extractor spring for $21.95 - might work for the OP, on both counts.

Here's the link

http://www.sprinco.com/tactical.html - part number 25006 is the combo option.

Edit...as an aside for folks that care about such things, a side benefit of the Sprinco spring is that it also seems to stop that well known AR "sproing" noise!

 

[Grey Morel]

Is this a 'widely known' thing with carbine gas systems breaking extractors? I have been shooting a bone stock DPMS carbine for two years now with no issues.

 

[ksfoa]

From my experience it has been an issue with some guns. I don't know how much quality plays a role but I had a Stag model 2 that had extraction/ejection issues. I got the BCM spring and o-ring kit and all was well afterwords. This issue started popping up after about 1200 rounds of all brass down the pipe.

 

[Z-Michigan]

Is this a 'widely known' thing with carbine gas systems breaking extractors?

More common than with rifle or mid gas systems, but no it's not that common anyway. I am not surprised that you haven't had a problem, most people won't. I suspect most problems are attributable to:
-poor quality or defective extractor to start with;
-oversized gas port - apparently some carbines (not quality ones) ship with ports as large as 0.10" or so, which is much larger than needed. For comparison, a Colt 6920 (16" barrel and carbine gas) has a 0.063" gas port.

 

[taliv]

The extraction system is perfectly fine for the rifle-length gas pressures it was designed for. Using the same extractor spring/insert in a carbine often causes problems. The workaround, as Bart said, is fiddling with a combination of action-spring/buffer weight and increasing the hardness (durometer rating?) of the insert and extractor spring.

(alternatively, an adjustable gas block, for match guns)

 

[rcmodel]

My 1970'ish Colt SP-1 carbine still has it's orginial extractor, and it is working just as good it always did.

No O-ring or Defender necessary. Just a carbine spring with a black insert buffer.

Maybe the next up-grade ought to be a real Colt mil-spec extractor, spring & black insert from Brownell's.

And I would also suspect your carbine barrel has a rifle size gas port causing the problems. (See post #8)

rc

 

[d2wing]

It seems to eject about 1-2 oclock so It seems the buffer and spring is the way to go. Thanks. The first 2 extractors lasted about 200 rounds so it might be overgassed as well.

 

[Bartholomew Roberts]

The other thing is that a carbine may run fine during your normal range use or plinking; but when you take it to a 3-day class where you are doing 1250 rounds over the class, it starts getting hot.

When it gets hot, the brass takes longer to shrink away from the chamber walls and is more "sticky." On many popular carbines, it is common for the "5.56" chamber to be a little tighter than real 5.56 specs in order to give better accuracy. They may also have cheaper buffer or springs or gas ports that are oversized. Throw in an extra 1.5" of dwell time compared to an M4 and what works fine normally stops working.

I've been to two classes now where students who never had problems with extraction had serious issues in class. One guy couldn't even finish the class it got so bad.

 

[d2wing]

Following the link provided I found that BHI (BlackHeart Int.) has a kit for $89 with all the parts I needed. I have already ordered them from different places but maybe this will save someone else the headache of looking all this up. It has the extractor, springs, and buffer with a spring. That site confirms what was posted, I need to get a heavier buffer, quality heavier springs
and a high quality extractor with spring and crane o ring. Since I have the BCM bolt, I can upgrade my old bolt for a spare. I only shoot a couple hundred rounds a year so it should be good.

 

[d2wing]

Good news, the BCM bolt and H2 buffer from Bravo co. arrived and are installed. No issues with a mag through it, ejects straight out, seems to be tamed down. The h2 buffer makes it smoother. The old buffer was much lighter and the old bolt had the old blue insert spring. Just mismatched parts.
The story is if you are having ejector problems look for an extractor spring upgrade and a heavier buffer.

 

[stubbicatt]

Wow. This makes me really appreciate the Kalashnikov.

 

[Mags]

Wow. This makes me really appreciate the Kalashnikov.

Did you even read the OP? The gun in question was a frankengun not a factory build. But thanks for your 2 cents...

 

[d2wing]

I run a very similar setup in my Smith and Wesson M&P15T - the same Sprinco (Red) buffer spring, but with the Spikes ST-T2 Buffer (tiny bit lighter than a H2 buffer). There is a huge difference over stock - so much smoother. Have had no reliability/cycling issues whatsoever. One thing to mention about the Sprinco spring.....they have a bundle where you can get the extra power spring plus a new heavy duty extractor spring for $21.95 - might work for the OP, on both counts.

Here's the link

http://www.sprinco.com/tactical.html - part number 25006 is the combo option.

Edit...as an aside for folks that care about such things, a side benefit of the Sprinco spring is that it also seems to stop that well known AR "sproing" noise!

Kwanger, I did order that kit from Sprinco and installed it today. It works great. Thanks.

 

[Onmilo]

It sounds like you have an out of specification bolt to me.
I would replace the whole bolt, not the carrier, just the bolt assembly, and see if the extractor breakage issue goes away.

 

[killchain]

Occam's razor:

Have you been shooting steel and brass mixed through it?

 

[d2wing]

Yup. New BCM bolt, no steel, surplus pr handload ammo just factory 55 gr loads. With the BCM bolt, H2 buffer, Sprinco red spring, it works fine. I am gong to upgrade the old bolt with Sprinco spring, Crane oring, and Les Baer extractor for a spare. It's been a learning experience.

 

[Old Scratch]

From the beginning, let me say that I have never been a big fan of the AR-15/M-16/M-4 series. They strike me as being too sensitive to gas fouling (for lack of a proper piston) as well as the particularly ill-advised use of ball powder (which is very sooty) in such a system.

In reading threads such as this, it strikes me that the world of AR-15/M-16/M-4 is dominated by tinkering with a bewildering array of mix-n-match, sometimes-it-works (and sometimes it doesn't) aftermarket parts.

My experience with such a scenario is limited to the 1911 pistol, which suffers from its own version of such really-wanting-to-believe-the-myth madness. For years, I endured tinkering, part-swapping and custom gunsmithing, only to end up with an extremely expensive .45 that was only partly reliable and marginally accurate. A stock .45 Glock later put it to shame in both categories.

We would all like to believe that our government puts our fighting troops into action equipped with only the finest equipment. The problem is that that may or may not be true. When companies start marketing full-length piston gas systems as a solution to armalite's problems, perhaps we should start paying attention; it is possible the emperor's clothes aren't quite what we thought they were.

At the risk of inciting vehement and irrational opposition, I posit the following: if the AK (and other rifles such as the FNC) provide weapons which require no such tinkering to approach reliability, perhaps the armalite designers missed the proverbial engineering boat. If it can't be relied upon to function reliably as it leaves the factory, what is the point?

 

[Kwanger]

Kwanger, I did order that kit from Sprinco and installed it today. It works great. Thanks.

Excellent - pleased it worked for you.

 

[Warbow]

At the risk of inciting vehement and irrational opposition, I posit the following: if the AK (and other rifles such as the FNC) provide weapons which require no such tinkering to approach reliability, perhaps the armalite designers missed the proverbial engineering boat. If it can't be relied upon to function reliably as it leaves the factory, what is the point?

Kind of off topic, but the design is fine. The vast majority of factory ARs run well out of the box and require no tinkering. Note that the rifle under discussion here is not a factory build.

I think the problem is the AR platform is a victim of its own success. They're so popular that there are dozens upon dozens of parts makers with dollar signs in their eyes and a lot of them are putting out parts as cheaply as possible with no mind whether the they will actually work well. It's no surprise that when someone builds a rifle with these cheap parts that it's going to have problems.

 

[Quentin]

Well said, Warbow!

 

[Bartholomew Roberts]

It's no surprise that when someone builds a rifle with these cheap parts that it's going to have problems.

Not only that; but apparently the rifle started working fine once the OP replaced those parts with parts that were built to the same standard (or better) that the original design demanded.

In reading threads such as this, it strikes me that the world of AR-15/M-16/M-4 is dominated by tinkering with a bewildering array of mix-n-match, sometimes-it-works (and sometimes it doesn't) aftermarket parts.

True; because the design is so modular that it is one of the few in the world that a guy like me, who can't even hang a shelf on a wall without spending 5 hours on it, can build a fully functional AR15 in an hour from a pile of parts.

The flip side of that is what Warbow described, not all of those parts marketed as "improvements" are and even with the ones that are, you have to understand how they affect the system as a whole before they will improve reliability.

For example, the LMT Enhanced Bolt Carrier is designed to "enhance reliability." It is made by a well-respected manufacturer with military contracts who recently won the UK's competition for a .308 AR. However, if you put it in a 20" barrel AR with a military spec gas port and chamber. you'll have function problems because it is desgined to increase reliability in 10.3" barrel short ARs. The extra vent hole in the carrier will vent too much gas in that scenario.

Of course, none of that stops someone who has a poor understanding of how the AR works from buying the "enhanced reliability" from a respected manufacturer and enhancing their rifle right into frustration.