M16 and M4 extractors

[Slater]

The following is extracted from the September issue of the Army's online PM site:


The M16 rifle and the M4/M4A1 carbine can now use the same extractor spring assembly. That means in the near future the M16 and M4 will also use the same breech bolt assembly.

The old extractor spring assembly, NSN 5360-01-424-5899, is still in stock and may be ordered for use on the M16. The old breech bolt assembly, NSN 1005-01-422-3770, is also still in stock and may be ordered only for the M16.

Once stock of the two assemblies is exhausted, order only the new extractor spring assembly, NSN 5360-01-505-2886. It's gold colored - the old one is dark colored. Order the new breech bolt assembly with NSN 1005-01-505-1035.


Is this gold colored extractor spring assembly already available commercially?

[cqbdriver]

I pretty sure this is the same spring. It is made by Colt & is gold color spring

http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=4840&title=EXTRACTOR%20SPRING%20ASSEMBLY&s=10818#10818

[Ridge_Runner_5]

Dont the M16 and M4 use the same bolt assembly anyway?

[Iraqgunz]

This extractor spring and insert is actually old and should be available. Originally the M16 rifle used a silver spring and blue insert. The spring and insert for the M4 was silver with a balck insert if I recall correctly. When it was discovered that there were some extraction issues they switched to the gold spring and black insert.

In order to simplify supply matters, the military decided that they could also use the silver/ black combo in rifles as well. I am sure that this new move is nothing more than even more simplification of the supply system and reduce confusion as to which extractor spring and insert is to be used.

[Iraqgunz]

The bolt yes. But by bolt assy. they mean the bolt complete with the extractor spring and insert. They had to differentiate them previously because of the different spring and insert.


Dont the M16 and M4 use the same bolt assembly anyway?

[jmart]

Dont the M16 and M4 use the same bolt assembly anyway?

No. The M4 bolt assembly includes the HD gold spring, the M16 bolt assembly includes the regular strength/blue insert extractor.

Now with this change they'll both use the HD spring, so whether an armorer orders from supply just the extractor, or the the entire bolt assembly, he'll get the same spring/insert.

[Blankwaffe]

Going a bit off the topic...

But does the military use the Crane o-ring in the rifle length extractor system as well?

Reason I ask is my new Armalite A4 20" came with the HD extractor spring,black insert and crane o-ring.
Extractor tension was so high that the extractor would chew the cartridge case rim when chambering.I also had a couple instances where the rifle failed to go into battery due to this.
Cartridge case ejection was erratic as well throwing cases all over the place with some just rolling out of the upper.Seems the extractor tension was also overcoming the ejector.
Now I dont know this for certain,but the extra resistance in the extractor seemed to be causing the cam pin to bear heavily on the upper receiver causing some odd wear.
I removed the o-ring from the extractor spring and all is well.Going into battery is smoother,ejection of the cases is consistant with cases landing in the same place,and it seems to have taken the shock/load off of the cam pin on the in battery stroke.
Up until recently all my rifles had the standard spring with blue or black buffer and no crane orings.
The HD extractor spring in the new Armalite does give more extractor tension than the old setup,but works perfectly.Honestly though I never had an issue with the standard spring and blue insert on the rifles.

Is it possible to have too much extractor tension?

[Iraqgunz]

I do not believe that a rifle type (like yours) require an O-ring. They are designed for carbines and SBR's. I do believe that in some cases too much extractor tension is a possibility. Save it for a rainy day or your next carbine purchase.

[Blankwaffe]

Roger that...I agree.Sure functions better without the crane o-ring.
This is the first Armalite upper I have purchased in many years,but it seems they have included some of the carbine features into the rifle length weapons like the M4 feed ramps and the carbine extractor spring,insert and o-ring.
So I take it that the military does not use the Crane upgrade on rifles?

[mndfusion]

My m-16 in basic training just had a spring, no insert or o-ring, I think it was an older a1 but I didnt know the difference back then anyway. I've read that using a D-ring eliminates the necessity to change the extractor spring on the M4 every 2000 rds.


The Counterpoise System
http://www.ketmer.com/armforte/cpoise/index.htm

Stoners associate Jim Sullivan (designer of The Counterpoise System), was involved the original AR-15 Project.

"The Counterpoise System consists of a new buffer assembly, drive spring and a counterweight which fits inside the bolt carrier of the rifle or carbine. It also includes a regulated gas tube for impulse adjustment and a "D" ring which installs beneath the extractor and eliminates M16/M4 extraction problems. "

[scottryan]

The black insert is not for carbines only.

It started being used on both carbine and rifles around 1997.

[scottryan]

No. The M4 bolt assembly includes the HD gold spring, the M16 bolt assembly includes the regular strength/blue insert extractor.

Now with this change they'll both use the HD spring, so whether an armorer orders from supply just the extractor, or the the entire bolt assembly, he'll get the same spring/insert.


Incorrect. The blue insert is not specific to rifles.

The only difference is the gold heavy vs. silver light spring.

[Iraqgunz]

Let me throw this out there to maybe shed more light. Don't forget that changes that happen in the military world do not always reflect what goes on on the civilian side.

To improve the reliability of the M4/M4A1 carbine, the Army has gone to a new extractor spring assembly for the carbine's breech bolt assembly, whose NSN is now 1005-01-505-1035 because of the new extractor spring.

The new extractor spring assembly comes with NSN 1005-01-505-2886. It’s gold colored with a black insert and will be added to TM 9-1005-319-23&P in Change 8. All M4/M4A1s should have the new extractor spring assemblies installed by June 2005. The M16-series rifle will continue to use the extractor spring assembly that comes with NSN 1005-01-424-5899 and is dark and has a black insert.

FOR MORE INFO, SEE TACOM MAINTENANCE ADVISORY MESSAGE MAM-04-024

[scottryan]

Let me throw this out there to maybe shed more light. Don't forget that changes that happen in the military world do not always reflect what goes on on the civilian side.

To improve the reliability of the M4/M4A1 carbine, the Army has gone to a new extractor spring assembly for the carbine's breech bolt assembly, whose NSN is now 1005-01-505-1035 because of the new extractor spring.

The new extractor spring assembly comes with NSN 1005-01-505-2886. It’s gold colored with a black insert and will be added to TM 9-1005-319-23&P in Change 8. All M4/M4A1s should have the new extractor spring assemblies installed by June 2005. The M16-series rifle will continue to use the extractor spring assembly that comes with NSN 1005-01-424-5899 and is dark and has a black insert.

FOR MORE INFO, SEE TACOM MAINTENANCE ADVISORY MESSAGE MAM-04-024

This is exactly what I was saying and does not jive with your original position.



Originally the M16 rifle used a silver spring and blue insert. The spring and insert for the M4 was silver with a balck insert if I recall correctly.


This original statement is incorrect.

The black insert started being used in 1997.

In the fall of 2003, the carbines received the gold colored spring while the rifles stayed with the traditional spring.

The black insert in itself is not carbine specific.

[Iraqgunz]

Let me clarify this. I should have said the M16A1/A2 rifle the extractor spring was silver and the insert was blue. Though the black insert may have been approved and theoretically been in use as early as 1997, I can tell you that the ones with the blue inserts were still be shipped from supply depots as recent as 2005-06. The original M4 extractor spring and inserts that I saw (in the MIL system) were silver w/ a black insert. Later they changed to the gold spring/ black insert.

When ordering extractor spring/ inserts for the M16A2/A4, etc.. IIRC you may still receive the older type until stocks are depleted. At one point there were 3 different ones in the system and it was my understanding that dropping the old one was to simplify procurement.

The military is not very keen about just tossing out parts even something as cheap as an extractor spring and insert and would rather use them up. I also did not intend to imply that the black insert is exclusive to the carbine.

If I misspoke or created confusion, I apologize.


This is exactly what I was saying and does not jive with your original position.



This original statement is incorrect.

The black insert started being used in 1997.

In the fall of 2003, the carbines received the gold colored spring while the rifles stayed with the traditional spring.

The black insert in itself is not carbine specific.

[scottryan]

Let me clarify this. I should have said the M16A1/A2 rifle the extractor spring was silver and the insert was blue. Though the black insert may have been approved and theoretically been in use as early as 1997, I can tell you that the ones with the blue inserts were still be shipped from supply depots as recent as 2005-06. The original M4 extractor spring and inserts that I saw (in the MIL system) were silver w/ a black insert. Later they changed to the gold spring/ black insert.

When ordering extractor spring/ inserts for the M16A2/A4, etc.. IIRC you may still receive the older type until stocks are depleted. At one point there were 3 different ones in the system and it was my understanding that dropping the old one was to simplify procurement.

The military is not very keen about just tossing out parts even something as cheap as an extractor spring and insert and would rather use them up. I also did not intend to imply that the black insert is exclusive to the carbine.

If I misspoke or created confusion, I apologize.



I was referring to new production guns.

Not old stock of parts.

[Bill Alexander]

This is good information, I regard the insert change as little importance as the specifications shift the hardness from 70 to 80 Mohr but given the tolerance range of urethane moulding compounds the soft and hard tolerances overlap.

Does anyone have access to the mechanical considerations for the new springs, including the material changes and wire diameter. It will be interesting to see how they approached the life cycle, given a fixed displacement in service, of increasing the operating forces, or if the material shift was to compensate for an agressive environment.

Bill Alexander