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Posted: 4/5/2013 12:24:20 PM EDT
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It was suggested to me in the Ammo forum that I reinforce my extractor spring with an o-ring, specifically a #40 Viton. My local hardware store, Lowes, and Home Depot all carry a large selection of o-rings, but not a #40 Viton-or even a plain #40. Is there another designation for this o-ring? Is Viton the maker or the material of which it's made?
Thanks Tom |
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Most everyone uses the "dash designator" Almost any industrial or hydraulic supply house will have them.
What you are looking for is a -006 o-ring. 1/8" X 1/4". Viton is the material. It's a little harder than buna and withstands the lubricants better. Additional Discussion |
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Quoted:
It was suggested to me in the Ammo forum that I reinforce my extractor spring with an o-ring, specifically a #40 Viton. My local hardware store, Lowes, and Home Depot all carry a large selection of o-rings, but not a #40 Viton-or even a plain #40. Is there another designation for this o-ring? Is Viton the maker or the material of which it's made? Thanks Tom You shouldn't have to use a crane o-ring for extraction. It should only be used as an emergency if you are experiencing failures. If your extractor spring is weak, simply replace it with a quality one. What is the exact issue that you are experiencing? Extraction problems can sometimes be related to other things. |
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The O ring is used as a band aid to allow chambers to self polish out through life fire and cleaning. A standard #60 O ring will fall apart in about 500 rounds due to CLP, and is about how long you should be running one if the chamber needs to polish in.
As for the stronger tension M-4 extractor springs, you have to remember whey Colt switched over to them in the M-4 rigs. The reason was not for M-885 or M-193 ammos, but when MK262 ammo was used in the rigs instead. The heavy bullet ammo uses slower burning powder get the round up to speed, which translate to the higher working pressures in the gas system since the peak dwell spike of the burn is closer to the gas port, which cause a tad bit of over function when the rifle cycles. The stronger spring just makes sure that the extractor does not slip off the rim on a harder spent case pull. Furthermore, since the extractor does have to slip over the rim of the live round at loading, adding both a extra tension extractor spring, then even ever more tension with an addition O ring, ends up with the rifle not being able to lock up correctly since the extractor now has too much tension and can not slip over the case rim at loading. So home depot or Ace for a standard #60 O ring, and if there is still a problem with standard 55/62 gr ammo and know that the standard extractor spring is correctly tension'g the extractor, then its time to evaluate the chamber conditions and/or gas port size, since you have have a larger problem then just a chamber that needed to be self polished through live fire. |
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http://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm%20extractor%20spring%20%203pack.htm
I run Bravo's Spring and Bumper on all my ar's. Even something like a new BCG, I will chuck the factory set up and install a Bravo. I don't use the O Ring that comes with the set up as I have seen this set up cause too much tension, that you can get Brass "SMEAR" on the face of the bolt. This 5 coil spring has just the right amount of travel. The Colt copper colored heavy spring is too stiff in my opinion. I would also suggest replacing them like every 2000 rounds. |
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