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 Bad ejection pattern
BamaInArk  [Team Member]
7/27/2010 6:33:31 PM EST
I posted this in the troubleshooting forum but didn't seem to get much attention. Reposting here.

I got a Spikes M4 upper, 1:7 twist with a BCM BCG. It's on a Spikes lower I assembled. The lower has an RRA LPK and am using a MilSpec tube with an H buffer. When I first assembled this gun I don't remember quite what the ejection pattern was but I don't think it was the way it is now. The gun probably has around 500 rounds through it.

I was shooting it less than 2 weeks ago with a friend when I really noticed what it was doing. Shooting from a bench most of the rounds land at the 1 to 2 o'clock position and remain on the shooting bench. No matter what rounds I run through it it ejects the same. We even tried to see if perhaps the rounds were bouncing off the ejection port deflector. Didn't look like it however. The time before I had shot it I had run a bunch of steel through it and didn't clean it. I was hoping after cleaning it good the ejection pattern would change. I cleaned it up good paying special attention to the chamber...chamber brush wrapped with a rag. I also disassembled the bolt completely and cleaned and lubed it good. Had a lot of of the red primer sealant in the bolt.

Today(a few days ago now) I finally got to shoot it again and I'm still seeing the same ejection pattern. The gun eats anything I feed it but just looks like a limp ejection. It locks back on every mag I try so I don't think it's under gassed.

Oh and one other thing I noticed today. I locked the carrier back and inserted a 20 round P-Mag. When I hit the bolt release the carrier went forward and sort of stopped as it was picking up the first round. As my mind was going wtf it then went all the way into battery. That makes me think something is dragging but didn't really detect anything. And it was plenty lubed up using Slip2000 EWL. Otherwise it runs fine except for the forward ejection pattern. I only ran one mag through it to see how it was ejecting after a thorough cleaning.

I think this might call for a heavier buffer...correct?

Any other suggestions?
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rychencop  [Team Member]
7/27/2010 6:42:19 PM EST
mine also spits them at the 2 o'clock position. i'm running a BCM bcg and ST-T2 buffer. i had the same pattern with the RRA 9mm buffer. mine also eats everything and has had zero malfunctions so i'm not going to worry about it. i think it has more to do with the bcg since my factory bcg and buffer put them in the 3-4 position.
shelbysguns  [Member]
7/27/2010 6:47:36 PM EST
On the slow bolt travel, try tuning your gas tube to align with the BCG. This might help?
AK_Steve  [Member]
7/27/2010 6:54:27 PM EST
Check the feed-ramp areas, maybe that's why the BCG is catching.
BamaInArk  [Team Member]
7/27/2010 7:03:46 PM EST
Originally Posted By rychencop:
mine also spits them at the 2 o'clock position. i'm running a BCM bcg and ST-T2 buffer. i had the same pattern with the RRA 9mm buffer. mine also eats everything and has had zero malfunctions so i'm not going to worry about it. i think it has more to do with the bcg since my factory bcg and buffer put them in the 3-4 position.


We did put my friends buffer and BCG in my gun to see if it made a difference. Same thing. He was shooting a Spikes SBR with the ST-T2 buffer.

I think you can also tune the extractor to change the ejection.

But it does make it easy to pick up your brass when it's sitting right in front of you!
TNRonin  [Member]
7/27/2010 7:37:24 PM EST
pull your charging handle, slide the BCG back in. does it move freely? If so check tube alignment, then check hammer for drag.
BamaInArk  [Team Member]
7/27/2010 8:05:01 PM EST
Originally Posted By TNRonin:
pull your charging handle, slide the BCG back in. does it move freely? If so check tube alignment, then check hammer for drag.


I did this with and without the bolt in the carrier. The BCG slides back and forth effortlessly. With the bolt in place I can easily push it into battery and remove it with my finger tip. With the bolt removed you can tell when the key contacts the gas tube but there is absolutely no resistance at all. I cannot see any marks on the bottom of the carrier or the top of the hammer so doesn't like it's dragging. With the receiver held vertical(normal shooting position) and sliding the carrier only(no bolt) back and forth you can definitely feel the friction more so than holding the receiver in the other 3 quadrants. But I suppose this is the normal way it rides on the upper receiver.

I think the initial delay in the carrier going forward was probably just a glitch. I only mentioned it in case it might be adding to the ejection issue.
LIL-COMMANDO  [Member]
7/27/2010 10:52:31 PM EST
There is no issue dont sweat it. I have a Colt 11.5 barrel with a H3 buffer and my rounds eject at 2 oclock. My 16" Colt w/H2 buffer ejects at 4 oclock and I have the heavy duty extractor spring on both guns. The two most common malfuctions are magazine related and extraction so if your rifle works fine in these two areas then dont start tweaking something that is not broken. I was using 5.56 55 gr M193 ammo...
InfiniteGrim  [Team Member]
7/27/2010 11:27:25 PM EST
Here is what the two rifles i have do....

Armalite 16" Semi auto BCG, carbine length gas system, spikes ST-T2 buffer brass goes 1-2 o'clock

Precision 18" AR, M16 BCG, midlength gas system, spikes ST-T2 buffer, the brass goes 4-5 o'clock.

If you dont already have an ST-T2 buffer, get one. The felt recoil is much smoother. Before getting the heavier buffer my Armalite ejected from 2-4 o'clock depending on ammo
fuzzy03cls  [Member]
7/28/2010 5:15:13 AM EST
What ammo are were you using? 5.56 & .223 will have different ejection because 5.56 is hotter.

BamaInArk  [Team Member]
7/28/2010 5:42:01 AM EST
Originally Posted By fuzzy03cls:
What ammo are were you using? 5.56 & .223 will have different ejection because 5.56 is hotter.



LC XM193(Black box, White box and Brown box), Q3131A1, Monarch brass(55gr fmj and soft point)), Monarch steel, Prvi Match 69 and 75 gr, Hornady 55 gr FMJs. They all eject in about the same spot. Didn't seem to make a difference which ammo I was using. That is one thing I thought was confusing.
fuzzy03cls  [Member]
7/28/2010 8:26:57 AM EST
That's odd. On my 3 AR's I eject closer to 2'oclock with all 5.56, & 3-4'oclock with any .223.
I don't think there's anything wrong or really anything to fix. If it extracts & ejects & keeps on going, I'd leave it be.
JoshAR  [Team Member]
7/28/2010 8:38:11 AM EST
If your gun goes BANG and cycles reliably you have no issues.
warpig8654  [Team Member]
7/28/2010 10:04:08 AM EST
Originally Posted By shelbysguns:
On the slow bolt travel, try tuning your gas tube to align with the BCG. This might help?


Ummm what?
shelbysguns  [Member]
7/28/2010 10:08:51 AM EST
Ummm what?

HIs gas tube might be slightly bent where it goes into the BCG, causing it to catch before the buffer shuts it. He laready checked and this isn't the problem. I hope you can understand this.
warpig8654  [Team Member]
7/28/2010 10:15:54 AM EST
Originally Posted By shelbysguns:
Ummm what?

HIs gas tube might be slightly bent where it goes into the BCG, causing it to catch before the buffer shuts it. He laready checked and this isn't the problem. I hope you can understand this.


Your post says tune, but I understand now that you meant turn.
shelbysguns  [Member]
7/28/2010 10:36:25 AM EST
Originally Posted By warpig8654:
Originally Posted By shelbysguns:
Ummm what?

HIs gas tube might be slightly bent where it goes into the BCG, causing it to catch before the buffer shuts it. He laready checked and this isn't the problem. I hope you can understand this.


Your post says tune, but I understand now that you meant turn.


I actally ment tune, like bend to align, but w/e you understand right?
Alpha-Romeo3  [Team Member]
7/28/2010 11:51:24 AM EST
Are you using the BCM extractor O-ring which should be included with your BCM BCG?

I've got two 16" carbine gas system, both are using BCM extractor upgrade kit, M16 auto BCG, H buffers, standard carbine action spring, one is a Colt 6721 with heavy barrel profile and the other a LMT M4 government barrel profile, with the noted setup they both ejects at about 4 o'clock using my 55gr and 62gr mil surplus ammo.


BamaInArk  [Team Member]
7/28/2010 2:47:59 PM EST
Originally Posted By Alpha-Romeo3:
Are you using the BCM extractor O-ring which should be included with your BCM BCG?

I've got two 16" carbine gas system, both are using BCM extractor upgrade kit, M16 auto BCG, H buffers, standard carbine action spring, one is a Colt 6721 with heavy barrel profile and the other a LMT M4 government barrel profile, with the noted setup they both ejects at about 4 o'clock using my 55gr and 62gr mil surplus ammo.




No...I left it out. Maybe I'll try that to see if it makes a difference. Couldn't hurt. I suppose I might try a heavier buffer to just to see if it makes any difference

Judging from the responses I might not worry about it too much. When I look at the ejection chart which recommends a 3 to 4:30 ejection it just makes me want to tweak to get it more perfect.
LIL-COMMANDO  [Member]
7/28/2010 5:37:43 PM EST
Ejection chart, I was never told about this in Colt Armorer School As long as the ejection and extraction work there is no issue....

Originally Posted By BamaInArk:
Originally Posted By Alpha-Romeo3:
Are you using the BCM extractor O-ring which should be included with your BCM BCG?

I've got two 16" carbine gas system, both are using BCM extractor upgrade kit, M16 auto BCG, H buffers, standard carbine action spring, one is a Colt 6721 with heavy barrel profile and the other a LMT M4 government barrel profile, with the noted setup they both ejects at about 4 o'clock using my 55gr and 62gr mil surplus ammo.




No...I left it out. Maybe I'll try that to see if it makes a difference. Couldn't hurt. I suppose I might try a heavier buffer to just to see if it makes any difference

Judging from the responses I might not worry about it too much. When I look at the ejection chart which recommends a 3 to 4:30 ejection it just makes me want to tweak to get it more perfect.


GHPorter  [Team Member]
7/28/2010 5:40:14 PM EST
Originally Posted By BamaInArk:
Originally Posted By Alpha-Romeo3:
Are you using the BCM extractor O-ring which should be included with your BCM BCG?

I've got two 16" carbine gas system, both are using BCM extractor upgrade kit, M16 auto BCG, H buffers, standard carbine action spring, one is a Colt 6721 with heavy barrel profile and the other a LMT M4 government barrel profile, with the noted setup they both ejects at about 4 o'clock using my 55gr and 62gr mil surplus ammo.




No...I left it out. Maybe I'll try that to see if it makes a difference. Couldn't hurt. I suppose I might try a heavier buffer to just to see if it makes any difference

Judging from the responses I might not worry about it too much. When I look at the ejection chart which recommends a 3 to 4:30 ejection it just makes me want to tweak to get it more perfect.
Perfect is "it eats everything," as you pointed out earlier. I think you have a really great working gun that just happens to not fit an arbitrary troubleshooting chart-because it isn't having any trouble. Don't sweat it.

Dipper  [Member]
7/28/2010 11:24:40 PM EST
It's overgassed...... if you reload or know somebody that does, try some light loads and see if the ejection comes towards 3:00.
Went through it with one of my rifles...... ejected the light loads fine at 3 and 4 o'clock.... hotter loads at 1 o'clock........ every time.
Hot loads barely cleared the bench and some landed right next to the rifle on the bench........ I had mine fixed because my brass was getting beat up and overgassed situation can be hard on parts.
Look at the edge of your ejection port right in front of the shell deflector and see if it is getting beat up.... look for signs of the brass hitting there instead of the shell deflector.

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