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11/27/2006 5:04:01 PM EDT
What are the exact dimensions of the O-ring used ti improve AR15 extraction? What material would the O-ring have to be made from?

I'm having trouble getting hold of the Crane extractor O-rings because most US gunshops do not send any order overseas, even those without "gunparts".
11/27/2006 5:41:47 PM EDT
[#1]
I think most people use a #60 o ring and just keep an eye on it.  They are cheap and you just change them frequently.  Decent substitute until you can get the real thing.
11/27/2006 6:36:49 PM EDT
[#2]
Ok, but what dimensions are the #60? They are not numbered that way here. Maybe due to the metric system.
11/27/2006 7:58:37 PM EDT
[#3]
IM me your address and I will drop one in the mail to you.  I have no way of measuring one but they don't cost very much.  You can then compare them at the store until you find the right one.
11/28/2006 2:15:21 PM EDT
[#4]

Quoted:
Ok, but what dimensions are the #60? They are not numbered that way here. Maybe due to the metric system.


1/4" OD,  1/8" ID, IIRC.
11/28/2006 5:13:08 PM EDT
[#5]
I found O-rings in that dimension made from a "special" rubber, Nitrile-rubber to be exact. This rubber will withstand petroleum-products and is supposed to tolerate temperatures up to 125oC / 257oF. These would be perfect for the job, right?

Thanks a lot for the help.
11/28/2006 6:07:46 PM EDT
[#6]
Should do the job reasonably well, yep

12/22/2006 6:24:43 PM EDT
[#7]
The NSWC Crane extractor o-ring is constructed of Viton.  OD is 1/4", ID is 1/8".  Thickness is 1/16"

You can order a bag of 25, Part No. ORV-006, for $2.65 from SmallParts.com  

/s/ Shawn Dodson
FirearmsTactical.com
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