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View Full Version : Failure to eject on new Stag Arms 16" upper



steve2267
09-05-06, 20:54
Summary:

Sunday I fired the first 120 rounds through a new 16" M4gery A3 carbine. The first few mags ran fine. Then I began getting failures to extract / eject. Either the spent shell was stovepiped, half sticking out of the ejection port, or it was still inside the receiver, more often than not wedged against the top of the receiver by the next round that had been stripped from the magazine and was trying to get fed up into the chamber -- it appeared to be a double feed, but one shell was spent (the top one) and the other shell was yet to be fired.

Details:

Brand new M4gery homebuilt:
lower: Rock River Arms lower with a RRA lower parts kit that I had installed
upper: brand new Stag Arms 16" AR15 A3 (flattop) complete upper (i.e. came fully assembled from Stag Arms)
ammunition: Winchester Q3131
magazines: used 20rd magazines purchased from someone on AR15.com

Note: before you start blaming the magazines, which I will admit could possibly be the problem, or contributing to the problem, please understand that these same magazines ran without nary a problem on a 20" Bushmaster A3 that I own. Also, my shooting buddy, Low Drag, fired my carbine and experienced a failure to extract/eject using one of his brand new 30rd magazines (that came with his new Bushmaster).

Initially no failures to extract/eject were noted. But as more rounds were fired, the problem occurred more frequently. By the last 20 rounds (rounds 100-120), the carbine had almost been reduced to a single shot.

The carbine had not been cleaned prior to firing. My bad. I will clean it thoroughly and lube it per TM 9-1005-249-10, which came with the Stag Arms upper.

The chamber appears to be smooth, well, smooth to my fingers anyway. The bore, chamber, and firing pin are chromed. The carrier key appears to be well staked -- it appears that the hex-head screws had been wapped with a chisel. A 1/8" hex key was too small for the hex-head, but a 9/64" hex key would not go in (due to metal deformation of the chiseling, perhaps?) I could not wiggle the carrier key by hand, as much as I tried, so it does not appear to be loose as best I can tell.

Removal of the bolt carrier and field stripping of the bolt revealed a lot of brass buildup underneath the extractor claw/groove. I cleaned this out with a Spyderco today. The extractor felt smooth to the touch, and close examination by eye; no burrs were found. However, there was NO o-ring around the extractor spring.

The vendor has initially blamed either ammunition (Winchester Q3131 -- although he did not know it at the time) or poor magazines, claiming the upper had been test fired at the factory (concluding apparently, that, the upper cannot be at fault).

Corrective actions I will be taking:

1) procure brand new magazines (any recommendations? I'm thinking D&H from 44mag.com or possibly the AR-Stoner mags w/ Magpul followers available at MidwayUSA)
2) procuring an o-ring for the extractor spring assembly here: http://www.adcofirearms.com/itemdetails.cfm?inventorynumber=2689
3) cleaning and lubricating the firearm

Any other suggestions? Why the extraction problems? Fitting a cartridge into the bolt face (with the bolt removed) seemed to indicate the extractor had a very good grip / fit onto the cartridge.

Thx for any help, insights, and/or recommendations.

steve2267
09-05-06, 20:56
Somehow I managed to double post. This thread is a duplicate; I suggest this thread be deleted.

Paulinski
09-05-06, 21:15
I had the exact same thing happend with my brand new stag 20" rifle. I fired about 90 rounds and started having issues like you mentioned. I relubed it with CLP and the problems went away.

Robb Jensen
09-06-06, 04:21
It sounds like you have a few problems.

1st, You need a lot of lube. The carrier should almost be dripping of oil.

2nd, It also sounds like you have weak extraction. Weak extraction will allow the ejector to overpower the extractor and can cause the release of the empty casing inside the upper receiver which can/will damage the carrier key or gas tube (causing further problems). You can remedy this with stronger extractor spring like a Wolff XP M4 extractor spring and/or a extractor enhancer like the MGI D-fender or Crane-O ring. On all my ARs 16" or under I use both.

3rd, If you have a carbine stock and I were you I would increase the weight of the buffer to an H2 or H3.

steve2267
09-06-06, 04:44
It sounds like you have a few problems.

1st, You need a lot of lube. The carrier should almost be dripping of oil.

2nd, It also sounds like you have weak extraction. Weak extraction will allow the ejector to overpower the extractor and can cause the release of the empty casing inside the upper receiver which can/will damage the carrier key or gas tube (causing further problems). You can remedy this with stronger extractor spring like a Wolff XP M4 extractor spring and/or a extractor enhancer like the MGI D-fender or Crane-O ring. On all my ARs 16" or under I use both.

3rd, If you have a carbine stock and I were you I would increase the weight of the buffer to an H2 or H3.

I'm not particular, should I get an H2 or H3 buffer spring / buffer assbly?

I found where I can purchase the Crane-O ring @ adcofirearms. Where else can I purchase the parts you mention? MGI D-fender and Wolff XP M extractor spring? (I suppose I can order the Wolff extractor spring directly from Wolff. Is it listed as "XP M4 extractor spring" in their catalog / on their website?

Since we were finding a lot of brass under the extractor, and since this is brand new, supposedly test fired at the factory... would you try the H2/H3 buffer first to see if everything else works? I would surmise that if it was truly test fired at the factory, and they had no issues, they would NOT have removed a Crane o-ring, or a Wolf XP M4 extractor spring... but could very well have used an H2 or H3 buffer spring.

Thanks for all your help.

Robb Jensen
09-06-06, 04:53
You can get the Wolff XP M4 extractor spring directly from them part #30090 www.gunsprings.com

You can get a H2 or H3 from G&R Tactical (http://www.gandrtactical.com/cmt.htm). Either one will work very well.

You can get the MGI D-fender from Brownells.

ArchAngel
09-06-06, 12:29
I had a similar problem that I diagnosed on a pre-ban CAR-15 that was an unknown/gunshow build that I bought from a friend way back.

Anyway, I had the exact same jam/failure to eject that you had.

What I found was the action was cycling too fast - in mine it is too much gas from an enlarged gas port under the FSB.

One of the first ways you can check is to put that upper receiver on a standard A2 buttstock receiver and fire it - it will probably cycle properly due to the length in the A2 Buffer Tube and spring.

My problematic upper ran fine when I did and you could feel the gas blowing out the action into my eye - not pleasant but a great tool.

My solution was to add a Wolff Xtra Heavy buffer spring and a rate reducer buffer that Brownells was carrying (I don't see the part there now) - so one of the heavier buffers should work.

Honestly - try that lower on an A2 stocked lower and see if you have a different result.

My fix was relatively cheap.

What I found was this CAR-15 was a "franken - build" and I've replaced parts for mil-spec in it and at some point I'll change the barrel out. It was bought during the ban very cheap as a pre-ban so I've never minded working on it and it's been a good learning tool. It runs 100% now.

steve2267
09-06-06, 17:24
Here's an update on my problem. Chris at Eaglefirearms said that Stag Arms would service the upper under warranty, but that all warranty issues have to go through them. So I called the number given and asked for Jessie, per my instructions. Jessie listened to my above description and said that "it shouldn't be doing that." He said it shouldn't need a Crane O-ring, or an enhanced Wolff extractor spring. He discounted it being a magazine issue. He didn't think that a heavier buffer would fix the problem -- that it "slows the cyclic rate" but doesn't necessarily slow down the bolt. While he declined to tell me what he thought might be wrong, he is e-mailing me a UPS label so that I can ship the upper back to him. He said it will take about two weeks for me to ship it to them, they diagnose the problem, repair or fix whatever is wrong, and ship it back to me.

So, whaddya all think? Should I just send it back for warranty service and wait to hear what they find / fix? I was kinda looking forward to tinkering around with a bunch of this stuff. The buttstock options are pretty easy to try out. I dunno about changing the extractor spring, or adding an O-ring -- while I certainly don't see any harm in it, and would like to give it a go... I could also see a manufacturer getting pissy and saying I've voided the warranty.

I can't go shooting this weekend anyway, so at most I might be out an upper the following weekend.

SuicideHz
09-06-06, 17:38
My bet is the barrel extension. I have a hunch the bolt lug notches are too sharp and are biting into the jacket.

C4IGrant
09-06-06, 17:56
Since the upper is from Stag and is covered under warranty, I would send it back for them to trouble shoot. I would however do the following before I did that:

Read this: https://www.m4carbine.net/showthread.php?t=31

After cleaning and lubing the weapon give it another go and see what you get.

If it was my weapon and didn't have a warranty, I would do the following:

1. Follow my above adivce about cleaning and lubing.
2. Replace the mags with some quality ones (like CProducts).
3. Get an extractor spring and a Crane O-Ring. Keep the spring as a spare and install the O-Ring.
4. Buy a quality CS buffer spring (like ISMI) and install it.
5. Buy an H2 or an H3 buffer and install it.

Springs in mags, bolt and buffers wear out (faster than most people think) so it is always good to have them around. Using a heavier buffer, increases lock time which in turn increases reliability. This is why Colt ships all the LE/Military Carbines with H2 buffers.


C4

steve2267
09-30-06, 21:14
Here's an update on my Stag Arms 16" M4 upper "problem".

Summary: There may be no problem after all.

Today Cameron, Low Drag and I went out to the range today to shoot rifles. After attempting to sight in a new Rock River Arms 16" Tactical Elite upper (hvy bbl profile), I shot the Stag Arms upper just to duplicate the problem. I was also going to video it. I was shooting brand new D&H 20 rd mags procured at 44mag.com and brand new 30rd D&H mags procured at BravoCompanyUSA.com. NO other changes from when I shot the Stag Arms upper 2-3 weeks ago. Hadn't cleaned it (shame on me), hadn't lubed it. Low Drag inspected it and told me it had plenty of lube. BOTTOM LINE: with the new D&H mags, NO PROBLEMS. AFter 20-30 rds, Low Drag recommended I fire 4 mags through her as quickly as possible... so we loaded up one 20rd mag, three 30rd mags, and ten rounds in one 30rd mag. I fired doubles, double taps, rapid fire as fast as I could pull the trigger. At slide lock, drop the mag and insert the new mag and keep firing. So I ran probably 100-120 rounds through the gun very quickly. No problems at all.

I have not changed buffers, buffer springs, extractor spring, or added a Crane o-ring. While I either have received all these items or am waiting for them to arrive, I had not installed them.

The best Low Drag and I can figure is that the other mags that I used a few weeks ago, that had not had any issues in a 20" Bushmaster A3, may have been extending up into the Stag Arms receiver just a little too far, that must have been rubbing on the bolt carrier, slowing it down just enough to cause the malfunctions.

I'm going to give her a good cleaning now, lube her, and install those M4 carbine mods, and go shoot her a lot more. I'll report back if I run into any further problems. I would never have believed that magazines could have caused an ejection problem... but I think it is right to immediately suspect mags for a lot of these AR problems.

Thanks for all your help.