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dpmsguy
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Posted: 10/31/2008 8:15:42 PM

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Hi,
Recently ordered some replacement parts to have on hand in case. Ordered some new extractor springs and they suggested some O-rings also. So I ordered a few. When I took extractor out for cleaning, my DPMS Lo-Pro Classic 16" has only extractor spring.
If I were to replace the spring, is it normal to just replace the spring and not bother with the O-ring unless there are extraction issues? Or do you all put the O-ring on even if you are not having any problems with extraction?
From some things I have read, it seems the O-ring is standard in new models with 14.5" barrels, but not those with longer barrels.
Thanks for replies!
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Posted: 10/31/2008 8:29:05 PM
I put a #60 o-ring on all my AR-15's extractor spring.
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AL_Safety
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Posted: 10/31/2008 11:21:25 PM
I put a milspec O-ring from Mcmaster Carr - don't have access to the part number right now in all of my AR's, except the one that has the Dfender xtractor ring. The cheap o-ring works just as well. I think it makes ejection more consistent, shrinks the size of the brass spread on the ground versus no o-ring, and I haven't had any issues with extraction, other than with steel case ammo in my stainless barrels after 100 rounds or so rapid fire. The problem with steel case ammo shows up quicker when I don't run the o-ring.
irag2362
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Posted: 10/31/2008 11:50:11 PM
I use #60's also and my AR eats everything now with out an issue..
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Posted: 6/27/2009 10:30:49 AM
i use 001 size
proguide
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Posted: 6/27/2009 10:55:16 AM
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ThePatriot556
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Posted: 6/27/2009 11:16:28 AM
Originally Posted By nationwide:
I put a #60 o-ring on all my AR-15's extractor spring.



The kind you buy at a hardware store?

Winn
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Posted: 6/27/2009 11:23:33 AM
[Last Edit: 6/27/2009 11:29:55 AM by Winn]
Originally Posted By dpmsguy:

... If I were to replace the spring, is it normal to just replace the spring and not bother with the O-ring unless there are extraction issues? Or do you all put the O-ring on even if you are not having any problems with extraction?

From some things I have read, it seems the O-ring is standard in new models with 14.5" barrels, but not those with longer barrels.

Thanks for replies!



Originally Posted By BravoCompanyUSA:

Originally Posted By Winn:

Additionally, a specific question for Paul ...

Which "combination" do YOU suggest/recommend for use in your 16" midlength uppers, as opposed to your 14.5" carbines?

IOW, for the 16" mid would you suggest … your BCM:

5 coil spring + black insert + O ring (the "full boat")

or

5 coil spring + black insert, but no O ring

(or perhaps some “other” configuration for a 16" mid ... not sure what that would be though)




I always believe there is more than one way to skin a cat. Therefore there are a variety of different extractor set ups working well for the shooter.

We have seen too much tension exhibit itself in the form of not fitting over the rim of the casing (and not feeding). We have also see it where it fits over the rim of the casing, but upon the ejection part of the cycle, the grip is so strong that it fails to eject. And once we saw a very strong extraction system work ok when everything was clean, but after high round counts and having a bolt gunked up, the extractor moved less freely, resulting in new extraction issues.

If using a BCM extractor spring, I have not found a carbine that “needed” the o-ring to increase extraction power and run properly. However, it has been theorized that the o-rings may offer additional assistance in extractor float issues.

Whichever way you set up the BCM spring, o-ring, BCM (“real deal”) black extractor buffer, we have yet to see a circumstance where it could not fix extractor tension issues.

16” middys will require less extractor tension to run properly than a 14.5” would.

On a 16” middy, we run a standard CAR buffer or H. (for auto, we run H)
On a 14.5”, we run a H or H2 (for auto, we run H2)

For me personally I just run the BCM spring and BCM black buffer insert in my BCGs. It has been 100% in the MK18s, BCM 11.5”, M4’s, Middys, and Rifle systems.

Hope this info helps,
Paul



http://www.ar15.com/forums/topic.html?b=3&f=118&t=408495&page=2


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Posted: 6/27/2009 11:23:45 AM
Originally Posted By ThePatriot556:
Originally Posted By nationwide:
I put a #60 o-ring on all my AR-15's extractor spring.



The kind you buy at a hardware store?



Those will work for all of us "range commandos." Real, MIL-Spec rings are more durable, though I can't see them being closer to size tolerances.

Here's the McMaster-Carr page for their MIL-Spec O rings. I can't remember which spec and what durometer standards the Crane rings are, but I'm sure someone will pipe up with the right numbers shortly.
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Posted: 6/27/2009 12:05:23 PM
size 001
MillerSHO
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Posted: 6/27/2009 12:16:19 PM
[Last Edit: 6/27/2009 12:16:48 PM by MillerSHO]
The O-ring that came with my BCM extractor upgrade kit was too tight.

It wouldn't cycle reliably with the O-ring.

So I did the upgrade without the O-ring and everything has been flawless.
FMJ
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Posted: 6/27/2009 12:43:19 PM
On the complete LMT upper I bought from Paul at BRAVOCOMPANY 4+yrs ago
I use the BCM Oring and spring

I had to use all my strength to get that extractor on

I did take it to the range to make sure it ran.

There is such as a thing called overkill and can cause jams

BTW a side note
I never had problems with the OLD BLUE INSERT AND SPRING (carbine/Rifle)
Ive shot alot of ammo in my day with this set up
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FMJ
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Posted: 6/27/2009 12:44:56 PM
Originally Posted By Winn:
Originally Posted By dpmsguy:

... If I were to replace the spring, is it normal to just replace the spring and not bother with the O-ring unless there are extraction issues? Or do you all put the O-ring on even if you are not having any problems with extraction?

From some things I have read, it seems the O-ring is standard in new models with 14.5" barrels, but not those with longer barrels.

Thanks for replies!



Originally Posted By BravoCompanyUSA:

Originally Posted By Winn:

Additionally, a specific question for Paul ...

Which "combination" do YOU suggest/recommend for use in your 16" midlength uppers, as opposed to your 14.5" carbines?

IOW, for the 16" mid would you suggest … your BCM:

5 coil spring + black insert + O ring (the "full boat")

or

5 coil spring + black insert, but no O ring

(or perhaps some “other” configuration for a 16" mid ... not sure what that would be though)




I always believe there is more than one way to skin a cat. Therefore there are a variety of different extractor set ups working well for the shooter.

We have seen too much tension exhibit itself in the form of not fitting over the rim of the casing (and not feeding). We have also see it where it fits over the rim of the casing, but upon the ejection part of the cycle, the grip is so strong that it fails to eject. And once we saw a very strong extraction system work ok when everything was clean, but after high round counts and having a bolt gunked up, the extractor moved less freely, resulting in new extraction issues.

If using a BCM extractor spring, I have not found a carbine that “needed” the o-ring to increase extraction power and run properly. However, it has been theorized that the o-rings may offer additional assistance in extractor float issues.

Whichever way you set up the BCM spring, o-ring, BCM (“real deal”) black extractor buffer, we have yet to see a circumstance where it could not fix extractor tension issues.

16” middys will require less extractor tension to run properly than a 14.5” would.

On a 16” middy, we run a standard CAR buffer or H. (for auto, we run H)
On a 14.5”, we run a H or H2 (for auto, we run H2)

For me personally I just run the BCM spring and BCM black buffer insert in my BCGs. It has been 100% in the MK18s, BCM 11.5”, M4’s, Middys, and Rifle systems.

Hope this info helps,
Paul



http://www.ar15.com/forums/topic.html?b=3&f=118&t=408495&page=2




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Posted: 6/28/2009 5:03:55 AM
Originally Posted By GHPorter:
Originally Posted By ThePatriot556:
Originally Posted By nationwide:
I put a #60 o-ring on all my AR-15's extractor spring.



The kind you buy at a hardware store?



Those will work for all of us "range commandos." Real, MIL-Spec rings are more durable, though I can't see them being closer to size tolerances.

Here's the McMaster-Carr page for their MIL-Spec O rings. I can't remember which spec and what durometer standards the Crane rings are, but I'm sure someone will pipe up with the right numbers shortly.


They also work for us "non-range commandos" too, as I do not consider myself any type of commando.
M4bangr
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Posted: 6/28/2009 4:51:35 PM
Wolff Xtra-power extractor springs available from Brownells work 100% in my rifles, no need for o-rings.
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Alpha-Romeo3
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Posted: 6/28/2009 5:47:52 PM
I use Crane O-rings on all my ARs, carbine, midlength, and rifle gas systems. (from Bravo Co. or ADCO)

On my carbine gas systems only, I use BCM extra power chrome silicon extractor springs.

All my ARs have improved extraction performance compared to factory setups, I also use M16 auto BCG on all of them.


YMMV

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Posted: 6/28/2009 5:54:22 PM
Generally I have used the MGI D-Fender in the past, but my Noveske came with a O-ring so I left it be. Until it gets chewed up and then I will replace it with a D-Fender.
knight_dive
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Posted: 6/28/2009 6:37:20 PM
These are the rings I use from McMaster Carr:

1201T16
(Same as 1201T111)
MIL-Spec Viton® Fluoroelastomer O-Ring AS568A Dash Number 006

About $5 for a 50 pack so you can share some with your friends.

I'm pretty sure the size should be 006 (1/8" ID and 1/4" OD) since near as I can tell an 060 is about 7 3/4" diameter. My understanding is that the one listed above is the same as the Crane o-ring, per several threads here last year, but I don't have any way to truly verify that. I can say that all three of my bolts use this o-ring and the black insert and have never had extraction issues, but that was also true of two of them before the o-rings. The third had the o-ring installed before use.
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lamarbrog
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Posted: 6/28/2009 6:58:17 PM
in 16" carbines and midlengths I don't use the rings. They make it more difficult to install the extractor... And I hav eno had extraction problems anyway.

I keep a few available, just in case that need arises... But I don't use them.
acman145acp
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Posted: 6/28/2009 7:02:32 PM

Originally Posted By knight_dive:
These are the rings I use from McMaster Carr:

1201T16
(Same as 1201T111)
MIL-Spec Viton® Fluoroelastomer O-Ring AS568A Dash Number 006

About $5 for a 50 pack so you can share some with your friends.

I'm pretty sure the size should be 006 (1/8" ID and 1/4" OD) since near as I can tell an 060 is about 7 3/4" diameter. My understanding is that the one listed above is the same as the Crane o-ring, per several threads here last year, but I don't have any way to truly verify that. I can say that all three of my bolts use this o-ring and the black insert and have never had extraction issues, but that was also true of two of them before the o-rings. The third had the o-ring installed before use.
Those are the same dimensions for a #60 o ring in the plumbing supply dept the plumbing ones are 1/16 thick

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Posted: 6/28/2009 7:19:07 PM
[Last Edit: 6/28/2009 7:20:12 PM by badazzar15]
McMaster-Carr has the correct Viton o-rings.

1201T16 (Same as 1201T111)

MIL-Spec Viton O-Ring AS568A Dash Number 006

In stock at $4.82 per Pack

This product is sold in Packs of 50
website: www.spikestactical.com
email: sales@spikestactical.com
phone: 407.928.2666
fax: 866-283-2215
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Posted: 6/28/2009 8:35:04 PM
I knew someone would chime in with the right details. Thanks badazar!

And I'm saving the info for later reference too! (I hope I remember where I put it later...)
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Posted: 6/28/2009 9:13:12 PM
Originally Posted By badazzar15:
McMaster-Carr has the correct Viton o-rings.

1201T16 (Same as 1201T111)

MIL-Spec Viton O-Ring AS568A Dash Number 006

In stock at $4.82 per Pack

This product is sold in Packs of 50


definitely go with viton. Haha I only use viton valve stem seals in all the engines i rebuild.
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Posted: 7/7/2009 10:39:28 PM
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EMSflyer
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Posted: 7/8/2009 8:07:19 AM
Thanks for the good info and tag to order some O rings for new build.
Mike1911
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Posted: 7/9/2009 8:11:51 AM
Thanks for the info, I just ordered a pack.
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