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Posted: 2/24/2006 12:26:08 PM EDT
[Last Edit: 3/7/2006 5:47:37 PM EDT by GotGuns]
I'm pretty much a noob with ARs, so bear with me. I got the '05 SEBR () and I finally got to take it shooting today. I had to go myself because nobody I know even knew ARs were legal to buy..... Anyhow, it's the first time I shot an AR rifle.

When I got it, I totally stripped it down, cleaned it up, and lubed it with CLP. I was probably a little generous with the lube.

When I shot it, about 60-70% of the time the casing would stay in the upper. I started out with just 1 round in the mag until I got comfortable. The bolt locked back every time. It seemed to be shooting accurately (as accurate as I would expect my first time shooting). Recoil wasn't bad at all. No FTFeeds or FTFires, (except when I had 2 in the mag and the first one didn't eject, the second round would get jammed up).

The extractor seems to be working ok. It is pretty stiff. The ejector is really stiff, but I guess it is supposed to be. The ejector can be pushed all the way down to the bolt. I would press down on the forward assist after chambering a round, but that didn't seem to help. Any ideas?

ETA it happend with both Black Hills 55gr .223 and Winchester Q3131 5.56.
Link Posted: 2/24/2006 12:46:41 PM EDT
It might be something as simple as the rifle needing to have a couple hundred rounds through it to break everything in. Make sure that there is no oil in the chamber itself.
Link Posted: 2/24/2006 4:46:21 PM EDT
I have had problems with the Winchester Q3131 in my rifle, and after doing some reading, (and calling Rock River), LOTS of other people have as well. Armalite even posted a waring about this ammo.

http://www.armalite.com/library/techBulletins/tb6.htm

I switched ammo, and have had no issues since.
Link Posted: 2/24/2006 7:13:54 PM EDT
Link Posted: 2/25/2006 1:57:12 PM EDT
Well, I took her out again today. Same problem, and it is pretty consistent (I'd say 9 out of 10 don't eject). This time I had my uncle with me, and he said that it looked like the bolt was not moving back, at least not all the way.

I tried manually cycling rounds (without firing) and there were no problems ejecting brass.

I tried shooting without the mag and it still would not eject. The casing would usually just get jammed between the bolt and the lugs.

The bolt locked back every time I shot the last round out of a magazine (which was also the first round since I couldn't load a mag with 2 rounds without a jam after the first shot).

The last shot I took, I had two rounds in the mag. The gun fired, the casing stuck in the chamber, but the bottom half inch of the casing was ripped clean off (as if I had cut the casing with a hacksaw). The top half was in the chamber, the next round was stuck in that casing, and the bottom half was floating around in the action? (where the bolt normally would be had it closed).

At that point the second bullet fell right out but I had to do a little work to loosen up the stuck casing so that it would fall out. I decided at that point to call it quits before I broke something.

That is the first time a casing did not extract. Normally they extract but do not eject and they get jammed up between the bolt and the lugs.

The extractor and ejector work fine when not firing the rifle. I tested both with a spent casing and by cycling ammo without firing. No hiccups until I actually fire the rifle. I haven't tried the O ring suggestion yet as I haven't had a chance to hit up Home Depot. Any other suggestions though on why this might be happening?
Link Posted: 2/25/2006 3:38:36 PM EDT
[Last Edit: 2/25/2006 3:40:18 PM EDT by M4Madness]

Originally Posted By GotGuns:
The gun fired, the casing stuck in the chamber, but the bottom half inch of the casing was ripped clean off (as if I had cut the casing with a hacksaw).



Case head separation. Sounds like either hot ammo, weak brass, or excessive headspace. If it's doing it with more than one brand of ammo, then it just about has to be excessive headspace.
Link Posted: 2/25/2006 6:19:03 PM EDT
[Last Edit: 2/25/2006 6:22:38 PM EDT by theshootersden]
As I first started reading it sounded like dropped extraction due to a weak extractor spring or bad extractor... After reading on it sure sounds more like ammo or chambering issues, as the Madness has already pointed out...

ETA: I just noticed your ETA on the ammo... Look into the chamber as being the culprit... The reamer used to chamber it could of left something behind...
Link Posted: 2/25/2006 6:34:18 PM EDT
Link Posted: 3/7/2006 5:47:16 PM EDT
Well, I finally tried the o-ring suggestion from Dano. Worked like a charm. Thanks Dano.

Oh, and BTW, Bushmaster rocks. I called them up about the problem and they sent me out a new extractor spring with an o-ring for free, no questions asked. Haven't even sent in my warranty card yet.

Of course I couldn't wait, so I went to Lowe's and bought the o-ring anyways.

BTW, they only came in packs of 10, so if anyone needs one, let me know.

Oh, and I regret to report that the beer keg is no longer in service.
Link Posted: 3/8/2006 12:17:11 PM EDT
Glad to hear that it's working, but how does beefing up the extractor correct case head separation?
Link Posted: 3/8/2006 12:30:24 PM EDT

Originally Posted By M4Madness:
Glad to hear that it's working, but how does beefing up the extractor correct case head separation?



I have no idea what, why, or how it works. I just know that I put a lot of holes in an empty keg in a minimal amount of time.

According to BM, the case head separation was a fluke since it only happened once and should happen consistently if there was a different problem.

Guess we'll just have to see if it happens again.
Link Posted: 3/8/2006 12:53:30 PM EDT

Originally Posted By M4Madness:
Glad to hear that it's working, but how does beefing up the extractor correct case head separation?



My exact thoughts too...
Link Posted: 3/8/2006 9:26:27 PM EDT
Link Posted: 3/9/2006 3:20:12 AM EDT
[Last Edit: 3/9/2006 3:24:55 AM EDT by metroplex]
Math is a universal/intergalactic language
1+1 = 2 in Arabic, Chinese, English, Gou'ald, etc...

The extra power extractor spring + O-Ring is somewhat of a band-aid fix. My guess is that there was not enough dwell time for the case to retract (pressure to subside) and the weak extractor spring allowed the extractor to "slip" from the rim as the gas pressure forces the bolt carrier back. I have heard that a heavier buffer will solve this problem, but then I have heard a heavier buffer can cause short stroke problems too In true ARFCOM fashion, I have both just in case.

If the O-ring works well, I would recommend the D-fender D-Ring. They carry a lifetime warranty and make the extractor function VERY stiff (almost like an AK extractor). I thought it would cause feeding problems, but I tested it using snap caps and it worked fine. I even have a chrome silicon ejector spring.

The 5.7x28 cartridge reaches up to 50,000 psi chamber pressure (quite a bit for a pistol cartridge), and FN Herstal designed the P90/PS90 barrel to recoil a bit (0.030") when you fire a cartridge to allow the pressure to drop before the breech block/extractor starts to really move back and extract the case. Same theory I guess.
Link Posted: 3/9/2006 4:54:44 AM EDT

Originally Posted By Dano523:
I could explain it to you guys, but since some of you may find the reasoning harder than Chinese math using a slide ruler to comprehend, we will just call it a trade secret and let it go at that.



In other words, the case separation was a fluke caused by a bad casing... It was ammo related, not extractor related...

The O-ring only fixed the dropped extraction problem, as it should of...

Since I majored in Chinese math, this equation was simple...
Link Posted: 3/9/2006 12:44:45 PM EDT
Ok, should I be worried about using this "temp fix"? From metroplex's comments, does this mean that my gas pressure is too high (hence the bolt is coming back faster than the bullet exits the barrel resulting in the bolt trying to remove the still-expanded casing). Does my gas system need tweaked? Or should I just shoot a lot of stuff and hope it breaks in?
Link Posted: 3/9/2006 12:58:09 PM EDT

Originally Posted By GotGuns:
Ok, should I be worried about using this "temp fix"?



Nah. I'm using both a D-Fender and Wolff extra-power extractor spring in my rifle with no problems whatsoever.
Link Posted: 3/9/2006 1:17:51 PM EDT
[Last Edit: 3/9/2006 1:19:10 PM EDT by metroplex]

Originally Posted By GotGuns:
Ok, should I be worried about using this "temp fix"? From metroplex's comments, does this mean that my gas pressure is too high (hence the bolt is coming back faster than the bullet exits the barrel resulting in the bolt trying to remove the still-expanded casing). Does my gas system need tweaked? Or should I just shoot a lot of stuff and hope it breaks in?



There's not enough "dwell time" - basically the case has not returned to its normal shape and the bolt is trying to extract it. There are frictional forces acting between the case and the chamber wall. A properly timed system (on a rifle for instance) will allow the bolt to extract the case just as the pressure drops, reducing the frictional forces. On a carbine, its a different story. Think about it like trying to pull a fat guy that is stuck in a tube. Trying to pull him out before the liposuction is done wastes a lot of energy and you may lose your grip. Now try to pull him out with 100lb-200lb less fat (smaller size).

I'm just saying the O-Ring is a temp fix, unless you got a Crane O-ring. The D-fender has a lifetime warranty but I have heard the Crane O-ring going 8k+ rounds w/o any problems, but YMMV.

I have heard of heavier buffers helping situations like yours, but if its working right now, I wouldn't worry too much.
Link Posted: 3/9/2006 3:24:51 PM EDT
Link Posted: 3/14/2006 1:48:47 PM EDT
Link Posted: 3/14/2006 2:16:05 PM EDT

Originally Posted By Dano523:
The sky is falling; the sky is falling!!!!!!!!
OK, now that everyone has that out of system, the basic low down.




I put my boots on and you better put on your hard hat...
Link Posted: 3/14/2006 7:22:30 PM EDT
[Last Edit: 3/14/2006 7:31:01 PM EDT by Dano523]
Link Posted: 3/14/2006 7:24:48 PM EDT
Link Posted: 3/14/2006 8:04:10 PM EDT
[Last Edit: 3/14/2006 10:22:23 PM EDT by walpur6isknight]
hello, I am new here. this is, my first post. I just bought a stag left handed rifle, m4a3, and I too have had a couple of the failure to ejects with it. I am going to take it out to the range tomorrow and shoot it some more. I hope it only needs a break in. Owning only 1 rifle, i think the m4a3 will work out very well.

Of course I need to replace the 870 I sold, because the m4a3 can't do it all.
(although I dream of a MASTERKEY!)

Then there is the last problem, the new SIG P220SAO, or Glock 21.

I am glad I found this forum, just browsing has given me some real insight to my new rifle, I just pray it turns out to be a good idea to go with the stag LH m4a3, might stock up on the LH specific parts just in case... (yes, I am a southpaw)

Sorry, I will shut up now!

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