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View Full Version : Do you use a D-Ring in your AR15?


riggins_83
July 12, 2012, 08:44 PM
Do you use a D-Ring in your AR15 extractor?

Sinlessorrow
July 12, 2012, 09:54 PM
they are not needed in 90% of rifles.

if you run a MK18 and are having issues with the proper extractor spring then use a donut.

if you have any 14.5"+ rifle you should be fine with just the proper spring.

by proper spring I mean the Copper colored colt extractor spring.

cannonfire
July 12, 2012, 09:59 PM
The D ring that holds the hand guards on? Yes I do

Sinlessorrow
July 12, 2012, 10:18 PM
canon the D-ring is the crane spec'd O-Ring that goes around the extractor spring, the part that holds your hand guards is called a Slip ring(or delta ring to some people)

Quentin2
July 12, 2012, 11:48 PM
Nope, don't use it in my BCM, ArmaLite or Daniel Defense - all 16" midlengths. Some shorter barrels with carbine length gas benefit from them, to positively extract brass before it has cooled and contracted.

cannonfire
July 13, 2012, 08:52 AM
Sinlesssorrow thanks. I always called it a delta ring so thought that's what he meant, always nice to learn something

madcratebuilder
July 13, 2012, 09:31 AM
Sinlesssorrow thanks. I always called it a delta ring so thought that's what he meant, always nice to learn something

Slip ring is the term used in the 23&P manual, Delta ring is from the Colt parts breakdown for the AR-15. Either one would be correct.

D ring is the D shaped rubber ring used to add tension to the extractor. It's the same thing as a regular O ring at a higher price. I got one with a group of parts I ordered online, didn't order it and it wasn't on the invoice. Still in the parts box. You can get the mil-spec O rings from Mc-Car for a $1 each. Only thing I have ever had to use a O ring with is a pistol build.

Quentin2
July 13, 2012, 12:28 PM
The "D-ring" madcrate described is also called a Defender or something like that and it is D shaped instead of a plain o-ring.

Anyway a proper extractor/spring/insert normally won't need either. Good to have one handy as a bandaid for a marginal extractor.

NickySantoro
July 13, 2012, 01:03 PM
If you need a D ring or an O ring for reliable function, you have an extraction problem that needs to be addressed, not have band aid applied.

Quentin2
July 13, 2012, 02:19 PM
If you need a D ring or an O ring for reliable function, you have an extraction problem that needs to be addressed, not have band aid applied.

True, which is why I used the term bandaid. Kinda like bailing wire, a temporary thing until you can fix it properly. Or see if it helps a range buddy who has a problem. Anyway I keep an extra O ring in the range bag, never used it though.

Sinlessorrow
July 13, 2012, 08:55 PM
not true, in some carbines(read: 10.5") a O-ring is usually required, but everything else should be fine.

Bartholomew Roberts
July 13, 2012, 11:42 PM
In the M4 carbine, you get what is called "extractor lift (http://www.dtic.mil/ndia/2003smallarms/din.ppt)" where the extractor lifts off the rim of the cartridge for a brief moment during extraction. Normally this is not a problem because the residual chamber pressure is enough to keep the empty casing on the bolt face until the extractor settles back down.

There are a couple of approaches that have been used to mitigate this. One is a redesigned extractor that uses a wider foot and two separate springs (like the Knights SR15E3). Another is to wedge an O-ring or Defender ring under the extractor so it has less room to lift. The main example I can think of is if you get a dinged case or a case with a little extra drag on it, it can fall off if the residual pressure is not strong enough and you'll get a failure to extract.

Quentin2
July 14, 2012, 12:11 AM
not true, in some carbines(read: 10.5") a O-ring is usually required, but everything else should be fine.

The use of an O-ring in shorter barrels was already mentioned above.

Sinlessorrow
July 14, 2012, 12:23 AM
I also think spring design plays a huge role in this.

the original Colt extractor spring was the best and the only AR-15 extractor spring that is not overstressed to the point of giving out early. with under a 40%MTS

the new Colt copper extractor spring is the second best with a slightly higher (i think) 45%MTS.(probably the best for the M4 and M4A1 as well as the MK18

90% of all commercial offerings are incredibly stressed from 50%-90%MTS.