“missing”? rubber gasket on extractor spring

IndyM4 · May 13, 2021, 07:42 PM

I recently purchased a new Colt M4 (CR6920). Following a YouTube video about cleaning my rifle prior to firing it for he first time, it showed/discussed a rubber o-ring/gasket around the spring in the extractor assembly. My new rifle did not have that rubber o-ring. (The YouTube video was several plus years old and was dealing with either a LE6920 or a SP6920). My understanding is that the new CR is identical mechanically to the older LE and the SP versions of the 6920.
Question: Did Colt discontinue the use of the rubber o-ring? Or is my rifle missing the o-ring and I need to acquire a replacement part prior to taking my first shot? Thank you.

stagpanther · May 13, 2021, 07:48 PM

Does the extractor do it's job? If so, I'd leave well enough alone.

imashooter · May 14, 2021, 06:53 AM

Some need it, most function well without it.

stagpanther · May 14, 2021, 07:05 AM

The O ring simply adds extra pressure to the extractor. You probably are overthinking your gun before you actually fire it. The worst that can happen is a fired case doesn't eject properly if something is wrong with the extractor--which I highly doubt would be an issue in a new rifle. All things being equal--an engineer at Colt will probably know more about your rifle than a video on YouTube (or an internet marksman like me LOL).

MarkCO · May 14, 2021, 09:22 AM

There is a rubber insert (black inside the gold spring for Colt) which I always run, and then the exterior O-ring. Some are "D" shaped and some are round. Use is by gun, if needed or not. In a significantly over-gassed condition with 5.56 pressure rounds, almost necessary. In most well tuned systems, not needed, and can actually impeded proper function.

denvernoob · May 14, 2021, 07:00 PM

Most of the Colt's I was issued in the Army didn't have the O-ring. Never had any problems.

JustJake · May 14, 2021, 08:51 PM

The O-ring is cheap insurance that works. It enhances extraction and thus lessens the risk of requiring a malf-drill to fix a jam-ski in a combat situation.

That's why you'll find them on extractors in the bolts of Mil M4s and other Mil-issued M16 variants.

Lot of dead soldiers since back in the 'Nam paid for these little improvements.

rickyrick · May 15, 2021, 10:53 AM

Never used one, I’d say some of mine are probably over gassed to boot.

I have extra bolts, never needed one.

If there is combat going on in my vicinity, I will leave the area.

If there is combat going on on my block or property, well... I probably wouldn’t have to much time left on this earth anyway to worry about a rubber o-ring.

If I find myself in combat with an AR that fails due to not having this o-ring, there is way more problems in the country than what little ole me could deal with anyhow.

I was a soldier for a long time, I’m not anymore. It’s a job I had when young, which I no longer posses the skills, physical prowess, or knowledge of tactics.

9x19 · May 15, 2021, 12:45 PM

The O-ring has become a fashion statement... and really isn't necessary in most guns. I've actually had to remove them from a couple of new BCGs as they put way too much tension on the extractor and the bolt wouldn't close over the rim of a cartridge.

HWS · May 15, 2021, 11:45 PM

The road to hell is paved with guys preemptively fixing their ARs when there is no problem.

HiBC · May 17, 2021, 01:37 PM

I know a little about the origins of that o-ring.

Its a legit SOCOM tested combat reliability upgrade for M-4 s.

I also know a little about moldable elastomers and making and running molds.

Considerable R+D and testing can go into the original. There is a correct durometer and material.

A well trained orangutan can make an o-ring mold. Regrind rubber overmolding for toothbrush handles will make a "rubber" o-ring.

They might sell,but that does not mean they are the o-ring SOCOM approved.

JustJake · May 18, 2021, 10:43 AM

Quote:

Its a legit SOCOM tested combat reliability upgrade for M-4 s.

Correct.

Someone understands it.

FrankenMauser · May 18, 2021, 10:58 AM

It doesn't need to be there unless you have extraction issues.

The o-ring was a stop-gap measure - or Bandaid, if you prefer.
It was a expedient repair initially put into place on M16A2s that had extraction issues with some ammo.

Over time, it became standard and was incorporated into M4 specs pretty much from the beginning.

It is unnecessary on most ARs. But because the gubmint does it on battle rifles, people think they need it, too.

Like staked gas keys that were staked because of some screws loosening during sustained full-auto fire, but are now unnecessarily found in most semi-autos. Because "gubmint wants it on battle rifles, so it must be good"...

May 13, 2021, 07:42 PM	#1
IndyM4 Junior Member Join Date: May 13, 2021 Posts: 1	“missing”? rubber gasket on extractor spring I recently purchased a new Colt M4 (CR6920). Following a YouTube video about cleaning my rifle prior to firing it for he first time, it showed/discussed a rubber o-ring/gasket around the spring in the extractor assembly. My new rifle did not have that rubber o-ring. (The YouTube video was several plus years old and was dealing with either a LE6920 or a SP6920). My understanding is that the new CR is identical mechanically to the older LE and the SP versions of the 6920. Question: Did Colt discontinue the use of the rubber o-ring? Or is my rifle missing the o-ring and I need to acquire a replacement part prior to taking my first shot? Thank you.

May 13, 2021, 07:48 PM	#2
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,789	Does the extractor do it's job? If so, I'd leave well enough alone. __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

May 14, 2021, 07:05 AM	#4
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,789	The O ring simply adds extra pressure to the extractor. You probably are overthinking your gun before you actually fire it. The worst that can happen is a fired case doesn't eject properly if something is wrong with the extractor--which I highly doubt would be an issue in a new rifle. All things being equal--an engineer at Colt will probably know more about your rifle than a video on YouTube (or an internet marksman like me LOL). __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

May 14, 2021, 09:22 AM	#5
MarkCO Senior Member Join Date: October 21, 1998 Location: Colorado, USA Posts: 4,308	There is a rubber insert (black inside the gold spring for Colt) which I always run, and then the exterior O-ring. Some are "D" shaped and some are round. Use is by gun, if needed or not. In a significantly over-gassed condition with 5.56 pressure rounds, almost necessary. In most well tuned systems, not needed, and can actually impeded proper function. __________________ Good Shooting, MarkCO www.CarbonArms.us

May 14, 2021, 08:51 PM	#7
JustJake Senior Member Join Date: August 12, 2020 Posts: 497	The O-ring is cheap insurance that works. It enhances extraction and thus lessens the risk of requiring a malf-drill to fix a jam-ski in a combat situation. That's why you'll find them on extractors in the bolts of Mil M4s and other Mil-issued M16 variants. Lot of dead soldiers since back in the 'Nam paid for these little improvements. __________________ I use the Jake Brake every chance I get. Don't care if it annoys you. Hear me now?!

May 14, 2021, 06:53 AM	#3
imashooter Senior Member Join Date: December 28, 2013 Location: Alabama Posts: 395	Some need it, most function well without it.

May 14, 2021, 07:00 PM	#6
denvernoob Member Join Date: March 2, 2019 Location: Denver, Colorado Posts: 33	Most of the Colt's I was issued in the Army didn't have the O-ring. Never had any problems.

May 15, 2021, 10:53 AM	#8
rickyrick Senior Member Join Date: March 15, 2010 Posts: 8,238	Never used one, I’d say some of mine are probably over gassed to boot. I have extra bolts, never needed one. If there is combat going on in my vicinity, I will leave the area. If there is combat going on on my block or property, well... I probably wouldn’t have to much time left on this earth anyway to worry about a rubber o-ring. If I find myself in combat with an AR that fails due to not having this o-ring, there is way more problems in the country than what little ole me could deal with anyhow. I was a soldier for a long time, I’m not anymore. It’s a job I had when young, which I no longer posses the skills, physical prowess, or knowledge of tactics.

May 15, 2021, 12:45 PM	#9
9x19 Senior Member Join Date: October 15, 1998 Location: Sherman, TX USA Posts: 3,750	The O-ring has become a fashion statement... and really isn't necessary in most guns. I've actually had to remove them from a couple of new BCGs as they put way too much tension on the extractor and the bolt wouldn't close over the rim of a cartridge. __________________ Make mine lean, mean, and 9x19!

May 15, 2021, 11:45 PM	#10
HWS Member Join Date: July 1, 2018 Posts: 90	The road to hell is paved with guys preemptively fixing their ARs when there is no problem.

May 17, 2021, 01:37 PM	#11
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,286	I know a little about the origins of that o-ring. Its a legit SOCOM tested combat reliability upgrade for M-4 s. I also know a little about moldable elastomers and making and running molds. Considerable R+D and testing can go into the original. There is a correct durometer and material. A well trained orangutan can make an o-ring mold. Regrind rubber overmolding for toothbrush handles will make a "rubber" o-ring. They might sell,but that does not mean they are the o-ring SOCOM approved.

May 18, 2021, 10:58 AM	#13
FrankenMauser Senior Member Join Date: August 25, 2008 Location: In the valley above the plain Posts: 13,424	It doesn't need to be there unless you have extraction issues. The o-ring was a stop-gap measure - or Bandaid, if you prefer. It was a expedient repair initially put into place on M16A2s that had extraction issues with some ammo. Over time, it became standard and was incorporated into M4 specs pretty much from the beginning. It is unnecessary on most ARs. But because the gubmint does it on battle rifles, people think they need it, too. Like staked gas keys that were staked because of some screws loosening during sustained full-auto fire, but are now unnecessarily found in most semi-autos. Because "gubmint wants it on battle rifles, so it must be good"... __________________ Don't even try it. It's even worse than the internet would lead you to believe.