I've heard it talked about, but I can't seem to find the thread. What size o-ring is used to upgrade the extractor and what is the "proper" way to install it?

Take your extractor to the hardware store and test fit the o rings to find the one that works. Seems like it is a 005 maybe? Just get one that fits right over the spring on the extractor.

I'm pretty sure it's the #60 o-ring. I keep both #47s and #60s in my emergency range kit, but the #47 looks a little big to me. I haven't had to use one -- I upgraded all my bolts to D-fender rings a year or two ago, and those don't seem to wear out.

That is the way to go along with a Wolf spring.

for five bucks, SAW has a speciality extractor spring with rubber bumper in it.  it also works fairly well.

I dont beleive in those contraptions. But to each their own. A defender website. http://www.powercustom.com/parts_ar15.htm

It would be a joke if you spend $15+ for an O(D) ring.

You can find the same quality O rings at your nearby Home Depot for $1 or less.

Ok what is being attempted here with these O and D rings is add a bit more pressure to the extractor rather like the M-4 extractor spring with it’s black insert. The black insert isn’t any stronger it is just a different color to signify a stronger spring. Now all of this was deemed necessary because of the M-4’s problems with extraction. You see with the shorter gas tube the gas pressure is higher and quicker resulting in higher cyclic rates so Colt came up with stronger extractor springs and heavy buffers to combat these ills. It has even evolved into the new two-extractor spring SOPMOD II bolts that LMT is selling in very small numbers at quite high prices. In my opinion these are all treatments of symptoms. The root cause of all this is the gas pressure and how quickly it hits the bolt. I believe the fix for ALL of this the PRI Fatboy gas tube that effectively reduces the gas pressures to that of a 20 inch barrel.
Now as far as going to a hardware store and finding an O ring, sounds good just make sure it isn’t going to disintegrate in whatever cleaning solution you use. I believe the D fender d ring is made of Viton and can with stand a great deal of heat and chemical abuse. So there is my take on the O ring debate.

IPSC_GUY (done spouting opinions for now) sends

Yep, the Defender piece is far more resilient than a hardware store O ring.  Those wear out rather quickly IMO.  Only tried 2 though.  Probably end up costing the same in the end.  But if you lose one over the other while cleaning you are out some significant bucks.

Er-Uh  IPSC GUY, there is alittle more going on with the LMT SOPMOD II bolts than two springs.

I'd go with the Defender D ring if I were you. Seems to be purpose made for that application.

I've always owndered why the PRI fat boy wasn't adopted as a SOPMOD bloc upgrade. SS makes it more resiliant than the stock Al unit, & its pressure reduction affect allows the ammo case more time to relax from its pressure-formed fit in the chamber, thereby easing extraction.

Perhaps because the fat boy also significantly reduces the full-auto ROF, and that could be counterproductive in some situations?

I have a fat tube -- the Hay River Trading one, not the PRI -- on my 11.5-inch upper, and the increased gas volume cuts the speed from 835 down to 685 rpm, which is on the low side. It's 100% reliable, but IIRC milspec leans toward the 750 rpm range.

Just a guess here.....

Back to the basic question I have to ask: has the LMT bolt/carrier been adpoted by the SOPMOD yet? Or is it one of the modified bolts/carriers that has been submitted to the SOPMOD for trial by one of the bidders (LMT)?

I guess I'm lucky. I've got about 4K through my Bushy and I've never had an extraction problem. I've never felt the need for any additional spring action on my extractor.

I do have a accu-wedge just cuz I couldn't stand the very slight wobble between upper and receiver.

My carbine has been 100% reliable with just the Wolff Extra Power extrator spring.  In my case I haven't seen any need for o-rings or the Defender.

I got a 10 pack of the Wolff Extra Power extractor springs for $19.95.  I put them in all my carbines and no problems.  It is a much easier fix if you have extraction problems.

Ya know...
my roommate’s M4s are both stock Bushmaster bolts and he has never had any trouble with them and they are Gemtech suppressed, which adds all manner of different dynamics to the gas system. Now I have had an extractor spring flatten out on me and it causes all manner of extraction problems. So When I went about fixing this I did put a D ring on my extractor but the real fix IMO was the Larger PRI gas tube. My rifle recoils less (not that 5.56 has heavy recoil) and I can double tap almost .4 seconds faster and the muzzle flip does seem to be less.

tony_k tell me about your Hay River Trading gas tube. I have never heard of them.

M4 Man I know that there is a lot more to the LMT bolt than just two extra springs, I just didn’t want to sound like Cliff from Cheers is all. Now will I ever buy one? Who knows. At the moment my M4 is running just fine and I have every confidence in the current set up. So, I probably will not unless they take a serious dip in price.

IPSC_GUY sends

Hay River Trading manufactures lots of interesting AR parts, like the shorty triangular handguard conversions. It was founded and is owned by Ken Drasen, who has been building ARs for years (his other companies were all anagrams of last name: Sendra, Nesard, etc.).

He has been selling fat gas tubes for five years or so. IIRC, the price is $25 each. My short upper was built a coupla years back, and has handled a LOT of heavy full-auto fire, with no apparent damage; it definitely holds up better than a standard tube. It does cut the ROF way back, as noted above.

Here's my shorty with the Hay River fat tube and shorty tri handguards. It's great when I'm in a retro mood:

[img]http://www.hunt101.com/img/014532.gif[/img]

Do you have a website for Hay River Trading? That looks kinda cool. I love triangular hand Guards. When i was in Desert Shield and Desert Strom I took a set with me and changed out my round ones on my A2. Got lots of strange looks for it.

IPSC_GUY sends

Ken doesn't have a web site, and I lost his email addy and phone in a recent hard drive crash .... but a coupla friends have bought from him, so I'll dig up the contact info for ya.

The ROF could be turned up by enlarging the bbl. gas port just enough to increase the cyclic rate w/o offsetting the improved extraction affect provided by the fat boy. An adustable gas system would help in this regard, but doesn't seem to be an issue, or otherwise it probably would have been included in the bloc 2 list of upgrade requirements.

Ah well...

A question for those who use "D-fender" type rings & extra power extractor springs... do you use the standard rubber insert in conjunction with these up grades, or is it unneeded?

Thanks.

Basko
E-mail me your address and send you a couple Viton o-rings for free. I bought a bag of them last year and I have a few lives worth now. It fits around the spring.

I was having extractor problems with a new 16" car upper. I was told that the pigtail gas tube was just for the 10" barrel. Now I hear A modified tube can solve over-pressure problems in the 16"er. So anyway I think I will try one. Where do you find a PRI Fatboy?

WES GRANT
[URL]MSTN.BIZ[/URL]

M4, thanks for the info. Mikke