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Posted: 1/8/2006 11:17:18 AM EDT
[Last Edit: 1/10/2006 10:52:26 PM EDT by ogcujo]
Which one is better for serious use? Are there any other upgrades I can do to increase reliability?
Link Posted: 1/8/2006 11:39:00 AM EDT
[Last Edit: 1/8/2006 11:45:22 AM EDT by twl]
Link Posted: 1/8/2006 11:53:14 AM EDT
I have a Dfender in my M16.. I have never had a FTE with this gun.
Link Posted: 1/8/2006 11:57:44 AM EDT
The Crane O-Ring is nothing more than a #4 O-Ring available for 35 cents at any hardware store. I use this is all my bolts and it works perfectly. Save the $10 on either unit and go to the hardware store.
Link Posted: 1/8/2006 12:02:04 PM EDT
I would think that the D-ring would be better than an O-ring just due to its shape alone. An O-ring gets pinched into the shape of a D when installed over an extractor spring anyway, so you might as well start with a D-ring in the first place to avoid stressing the ring. Who knows?
Link Posted: 1/8/2006 12:09:35 PM EDT
Link Posted: 1/8/2006 12:16:56 PM EDT
[Last Edit: 1/8/2006 12:18:55 PM EDT by Yojimbo]
Personally, I prefer not to add extra parts if possible so I would try using either a SAW or Wolff extra power extractior spring by itself first.

I run only the Wolff extractor spring on my carbines and I've found no need use any additional parts even with Wolf.

One carbine is high milage with over 9500 rounds and the other is a newer mid-length with about 1500 rounds through it. As always, YMMV.

As to your original question, I would say that the D-fender is the better product because it's actually designed for this task and it looks like it's pretty much indestructable. That being said it still looks like the Crane O-ring will do the job but it will need to be replaced sooner which shouldn't be an issue because costs a lot less too.

If I ever needed one I'd would go with the D-fender.
Link Posted: 1/8/2006 12:38:31 PM EDT
I went with the D rings b/c they are proven to something like 30k rounds. This means that it will not be the cause of a stoppage.

To my knowledge noone has put standard, or even Viton, O rings to this test. Am I wrong?

Sam
Link Posted: 1/8/2006 12:44:23 PM EDT
Link Posted: 1/8/2006 12:51:41 PM EDT
This may be splitting hairs, but the composition of the issued Crane O-ring is different than MOST store-bought versions.

The store bought #60 O-ring is typically made of BUN-A, whereas the Crane variant is something different (name of material slips my mind at the moment). Suffice it to say, BUN-A is less resistant to heat and solvent.

This is likely a non-issue with regular replacement of the part. Changing out the 10 cent O-ring every time you perform PM will prevent any issues from arising.

The D-fender is also a good part, and I would not hesitate to use one of those either. Either of them are cheap insurance, and are a VERY good idea if you are running a short format gun (11.5 or 10.5 inch barrel).

Tim
Link Posted: 1/8/2006 12:55:14 PM EDT
[Last Edit: 1/8/2006 12:56:26 PM EDT by ogcujo]
Are there any other upgrades I can do to increase reliability? I'm getting the D ring but is there something else I could use?
Link Posted: 1/8/2006 1:02:20 PM EDT

Originally Posted By ogcujo:
Are there any other upgrades I can do to increase reliability? I'm getting the D ring but is there something else I could use?



See this thread for starters...

www.ar15.com/forums/topic.html?b=3&f=118&t=257301
Link Posted: 1/8/2006 1:06:48 PM EDT
Link Posted: 1/8/2006 1:17:17 PM EDT

Originally Posted By ogcujo:
Which one is better for serious use? Are there any other upgrades I can do to increase reliability?


I'm using Wolff extra power extractor spring for my SHTF gun and it runs fine.

If I ever have any problems with it I'm going to use a D-Fender or O-ring which is always in my tool box.

My other guns have Crane O-rings which I got from ADCO.
Link Posted: 1/8/2006 1:18:13 PM EDT
I have a D-Fender on one carbine, and a Crane O-ring on another. They both seem to work as advertised. But then again, my carbines ran fine without them, too.

I'll stick to the $1.00 insurance from now on.
Link Posted: 1/8/2006 3:59:38 PM EDT
Link Posted: 1/8/2006 4:15:53 PM EDT
[Last Edit: 1/8/2006 4:16:14 PM EDT by Yojimbo]
To guys who run the D-Fender or Crane O-rings:

Do you guys also run an extra power extractor spring?

The reason I ask is from what I remember Crane Reliabilty Parts Kit #2 contains both extra power extractor springs and o-rings. So I assume Crane prefers to use both and more extractor tension good for reliablity.

Is it possible to have too much extractor spring tension? If so what side effects might result by using both?
Link Posted: 1/8/2006 4:42:03 PM EDT
I think the crane o-rings are made of a special vitton rubber that the space
shuttle seals were made out of or at least that is similar to what I have been told.
Link Posted: 1/8/2006 4:49:31 PM EDT

Originally Posted By FlyingFive0:
I think the crane o-rings are made of a special vitton rubber that the space
shuttle seals were made out of or at least that is similar to what I have been told.



So we shouldn't use them in freezing weather?

Just kidding. (but couldn't resist the irony).

I'm a big fan of the crane O-ring, and use it in my 10.5" AR (thanks again, Steve!)



... and I have no doubt that the D-fender works awesomely as well. Both designs seem proven and effective.
Link Posted: 1/8/2006 4:50:56 PM EDT
[Last Edit: 1/8/2006 4:51:14 PM EDT by FlyingFive0]

Originally Posted By DK-Prof:

Originally Posted By FlyingFive0:
I think the crane o-rings are made of a special vitton rubber that the space
shuttle seals were made out of or at least that is similar to what I have been told.



So we shouldn't use them in freezing weather?

Just kidding. (but couldn't resist the irony).

I'm a big fan of the crane O-ring, and use it in my 10.5" AR (thanks again, Steve!)



... and I have no doubt that the D-fender works awesomely as well. Both designs seem proven and effective.

That my friend, was a good one
Link Posted: 1/8/2006 4:54:43 PM EDT

Originally Posted By Yojimbo:
To guys who run the D-Fender or Crane O-rings:

Do you guys also run an extra power extractor spring?

The reason I ask is from what I remember Crane Reliabilty Parts Kit #2 contains both extra power extractor springs and o-rings. So I assume Crane prefers to use both and more extractor tension good for reliablity.

Is it possible to have too much extractor spring tension? If so what side effects might result by using both?



I use both a D-Fender and a Wolff extra power extractor spring in my rifle, and have never had any problems with the combination.
Link Posted: 1/8/2006 5:13:51 PM EDT

Originally Posted By Yojimbo:
To guys who run the D-Fender or Crane O-rings:

Do you guys also run an extra power extractor spring?

The reason I ask is from what I remember Crane Reliabilty Parts Kit #2 contains both extra power extractor springs and o-rings. So I assume Crane prefers to use both and more extractor tension good for reliablity.

Is it possible to have too much extractor spring tension? If so what side effects might result by using both?



The only problem that I see using both is if you have a weak CAR recoil spring with some type of heavy buffer, the bolt may not lock all the way into battery because of the spring tension on the extractor. I had this problem last weekend on my SPR. I could not figure out why the round didnt fire. Everything looked good and the firing pin struck the primer.
I talked to Grant and he told me that this may be my issue.

I bought one of his new style recoil springs with a lot more tension. This solved the problem of the bolt not going into battery. I kept the wolf extractor spring and viton Oring. The rifle runs like a champ.
Link Posted: 1/8/2006 5:31:17 PM EDT
So where does one get a D-Fender ring?
Link Posted: 1/8/2006 5:49:11 PM EDT
I have a D-fender and wolff extra power spring, and my AR flings brass into one nice pile.
Link Posted: 1/8/2006 5:57:36 PM EDT
i use the d-fender in all of my rifles with no extraction problems before or after install.
Link Posted: 1/8/2006 6:20:16 PM EDT
Link Posted: 1/8/2006 6:30:16 PM EDT

Originally Posted By Homeinvader:
The Crane O-Ring is nothing more than a #4 O-Ring available for 35 cents at any hardware store. I use this is all my bolts and it works perfectly. Save the $10 on either unit and go to the hardware store.




35 cents?


I bought 500 of them off of Ebay for $5. I change them out a few times a year.



If my life depended on my rifle daily, I would go with the designed for the cause version.


It doesnt, so I dont.



Link Posted: 1/8/2006 6:46:30 PM EDT
[Last Edit: 1/8/2006 6:47:38 PM EDT by JackalAR]
I have a D-Fender in my new middy (CMT bolt) with 250 rds. of Q3131 down it. Seems to do the job more than well enough. You can see where the extractor was on the case rim, but it hasn't been an issue yet and the extractor looks perfect. I think the use of both is a little overkill, IMO. I like the D-Fender because it's only $13 on something you'd trust your life to and considering how much the rifle is worth... it's probably the cheapest part on it. Also designed by someone who should know what they're doing.

You asked about other things to increase reliability...well, first off it's unusal for me to stray from the original design so for me to use the D-Fender is a stretch, but I also decided to go with a CMT "H buffer" for the added .8 oz. of weight. My brass hits the very front edge of the brass deflector half way up the case and flys off at 1:30 - 2 o'clock. I also am a believer in ISMI springs, so I got a David Tubb CS ISMI flat-wound recoil spring. I spared no expense in my build, and these are the only "extras" I added. Barrel is 4150 CMV and bolt is MP checked.

You're favorite ARFCOM supporter should have the D-Fender...including the ones who replied to this thread.
Link Posted: 1/9/2006 1:57:53 PM EDT

Originally Posted By Yojimbo:
To guys who run the D-Fender or Crane O-rings:

Do you guys also run an extra power extractor spring?

The reason I ask is from what I remember Crane Reliabilty Parts Kit #2 contains both extra power extractor springs and o-rings. So I assume Crane prefers to use both and more extractor tension good for reliablity.

Is it possible to have too much extractor spring tension? If so what side effects might result by using both?



As a minimalist I did not go with the D-ring just b/c I thought it would be a good idea. One of my 11.5s had a severe case of dropped extraction about once or twice/mag dump. Another 11.5 - with lower round count - does not have this problem, so does not have a ring.........yet. The D ring is/was the only modification I made to the extractor on the problem upper. I have not had even one more failure to extract since doing so. We're talking about 3k rounds downrange with this particular upper since adding the ring.

I doubt that adding the spring would cause a problem. But it was just not necessary. I haven't needed one for the 14.5s. Nor do I feel any need to use rings or HD springs with any full length gas system uppers.

Sam
Link Posted: 2/20/2006 2:21:02 PM EDT
Viton isn't rated for arctic use (only down to -10F).
Link Posted: 2/21/2006 1:36:09 AM EDT
I've looked at this again and I don't understand how the springs "wear out" when you're dealing with chrome-silicon or Wolff extractor springs, which are generally rated for compression cycles in the hundreds of thousands (i.e. 500,000 compression cycles). The extractor does not completely compress/relax the spring. Has anyone worn out their 4-coil CS extractor spring or their Wolff spring? The cheaper springs are more likely to lose their spring rate due to material fatigue since the coils are thinner (wire diameter plays a role in spring rate based on material choice).
Link Posted: 2/21/2006 2:26:47 AM EDT
There is no difference between the O ring that Crane had produced and the D-fender in the minds of the folks in the SOPMOD project. The O ring, like the Crane Carbine Stock were projects that they developed in house, that after development and testing, found that there were similar items off the shelf that did just as good if not better than what they developed in house.

The above info came from someone involved in the SOPMOD project that I served with in Panama.

Link Posted: 2/21/2006 7:09:29 AM EDT
Link Posted: 2/21/2006 7:15:34 AM EDT
[Last Edit: 2/21/2006 7:16:08 AM EDT by JackalAR]
No kidding, what's $10 more to someone who has already made their mind up that they needed the added insurance already? Come on now...it's a one time cost. Hell, I even purchased a second D-Fender just in case.
Link Posted: 2/21/2006 7:20:03 AM EDT
[Last Edit: 2/21/2006 7:29:35 AM EDT by metroplex]
Has NSWC experimented with as FEW parts as possible? I find it surprising that they would require the 1 piece gas ring, extractor insert, 4-coil CS extractor spring, CS ejector spring, AND the O-Ring all used at the same time. It would be more cost effective to use only the most vital parts.
Link Posted: 2/21/2006 8:26:55 AM EDT
How does the Armforte D-Ring compair to the MGI brand name D-Ring?
Link Posted: 2/21/2006 8:29:41 AM EDT
Question: Isn't it true that the D-Fender was designed for use with the blue insert extractor spring?
Link Posted: 2/21/2006 8:34:49 AM EDT
[Last Edit: 2/21/2006 8:37:34 AM EDT by twl]
Link Posted: 2/21/2006 8:48:47 AM EDT
If anyone has that much of a hard-on to increase extractor spring tension the D-Fender hands down is the best way to go. I personally don't like to deviate from the original design so *if and when* my extractor starts to act up I'll more than likey just replace the spring with something from Wolff.

Link Posted: 2/21/2006 8:51:23 AM EDT

Originally Posted By ogcujo:
Are there any other upgrades I can do to increase reliability? I'm getting the D ring but is there something else I could use?



Yeah! Quit messing around with what isn't broke, and leave the junk out of your gun.
Link Posted: 2/21/2006 10:39:43 AM EDT
[Last Edit: 2/21/2006 10:50:55 AM EDT by JackalAR]

Originally Posted By twl:

The D-Fender was actually designed to have no "insert" in the spring.
The D-Fender increases extraction force by 4x, all by itself.



...so would you recommend removal of the spring insert all together, removal of the D-Fender, or change the spring out for the black insert spring in a mid-length carbine? Does this 4x extraction accelerate extractor wear? With blue insert spring and D-Fender, I am ejecting at 1:30 - 2:00 after bounding off the leading edge of the brass deflector. This is with enhanced carrier, "H" buffer, and ISMI recoil spring.
Link Posted: 2/21/2006 11:47:00 AM EDT
tag
Link Posted: 2/21/2006 12:42:31 PM EDT
Link Posted: 2/21/2006 12:52:02 PM EDT
I thought the spring insert was added to "greatly increase spring life" by acting somewhat as a "buffer". Will removal not have any negative effect on the spring itself?
Link Posted: 2/21/2006 12:53:27 PM EDT
[Last Edit: 2/21/2006 5:48:13 PM EDT by Va_Dinger]
I have used both the D-Fender & ADCO CRANE o-ring, both with zero problems. I only switched to using the Adco o-rings exclusively because they have proven themselves and only cost $1 each. I also inspect mine every time I clean my weapon and change them out if they show any wear. I would never trust a manufacturer claim that either one will "Out live your barrel". That sounds fishy to me.
Link Posted: 2/21/2006 5:27:53 PM EDT
I use the oring - threw the d ring out.
Link Posted: 2/21/2006 5:33:56 PM EDT
[Last Edit: 2/21/2006 5:34:42 PM EDT by JackalAR]

Originally Posted By GETSUM:
I use the oring - threw the d ring out.



Any reason or are you just trying to show your ass?
Link Posted: 2/21/2006 6:36:01 PM EDT
[Last Edit: 2/21/2006 7:17:20 PM EDT by twl]
Link Posted: 2/23/2006 12:16:14 PM EDT
I got my D-Fenders today and they're not blue, but rather a black/gray color.
I was hesistant to lay down $10 for one, but if they're expected to last/outlast the life of the barrel, I might as well give it a try.
Link Posted: 2/23/2006 12:25:46 PM EDT
The D-Fenders haven't been blue in YEARS from what I remember...the blue insert I was referring to was the one in the spring itself.
Link Posted: 2/23/2006 1:21:13 PM EDT
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