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Old May 13, 2021, 07:42 PM   #1
IndyM4
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“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.
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Old May 13, 2021, 07:48 PM   #2
stagpanther
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Does the extractor do it's job? If so, I'd leave well enough alone.
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Old May 14, 2021, 06:53 AM   #3
imashooter
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Some need it, most function well without it.
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Old May 14, 2021, 07:05 AM   #4
stagpanther
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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).
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Old May 14, 2021, 09:22 AM   #5
MarkCO
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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.
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Old May 14, 2021, 07:00 PM   #6
denvernoob
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Most of the Colt's I was issued in the Army didn't have the O-ring. Never had any problems.
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Old May 14, 2021, 08:51 PM   #7
JustJake
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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.
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Old May 15, 2021, 10:53 AM   #8
rickyrick
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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.
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Old May 15, 2021, 12:45 PM   #9
9x19
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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.
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Old May 15, 2021, 11:45 PM   #10
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The road to hell is paved with guys preemptively fixing their ARs when there is no problem.
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Old May 17, 2021, 01:37 PM   #11
HiBC
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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.
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Old May 18, 2021, 10:43 AM   #12
JustJake
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Quote:
Its a legit SOCOM tested combat reliability upgrade for M-4 s.
Correct.

Someone understands it.
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Old May 18, 2021, 10:58 AM   #13
FrankenMauser
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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"...
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