Failure to eject - .308 18" barrel - Page 1

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[ARCHIVED THREAD] - Failure to eject - .308 18" barrel

Posted: 1/28/2018 1:30:55 AM EDT

I recently put together a .308 (Thunder Tactical upper with an 18" bbl) and I'm having trouble with extraction / ejection. The first time I took it out I used some cheap Wolf steel case (I know, I know, but I'm poor and it's what I had on hand) and put about 30 rounds through it. It failed to extract multiple times, leaving me to have to pry the case out of the chamber with my fingernail.

Today, I took it out again and put some much nicer nickel plated ammo through it. This time, instead of just flat failing to extract, it would fail to eject the case. Several times the empty case itself was turned completely backwards in the chamber, causing it to jam. Several other times it would stovepipe. I was lucky to get five rounds through it before it would fail to eject. I tried several different mags but I only had one type of ammo (can't remember what it is off the top of my head, but it's nice and nickel plated). I think I put about 50 rounds through it.

Here is a photo of a backwards case stuck in the chamber:

Attached File

Suggestions? New extractor, maybe, or is it just having teething problems?

Posted: 1/28/2018 8:29:52 AM EDT

[#1]

What's the extractor spring arrangement looking like?

Any denting on the cases?

I'm leaning toward not enough extractor spring tension, and possibly over gassed on the upper.

Posted: 1/28/2018 8:46:24 AM EDT

[#2]

What length gas system? And who’s your bolt carrier and bolt from?

Posted: 1/28/2018 9:04:15 AM EDT

[#3]

Could be too much extractor spring tension. Some 308 BCGs have two rubber o-rings in them. Removing one clears things right up, if that's the issue.

Does it lock back on a single round? Where does the brass eject, when it does eject?

-Stooxie

Posted: 1/28/2018 9:05:49 AM EDT

[#4]

OP, love the avatar, btw. Roy Fokker's VF-1s. Brings back the memories.

-Stooxie

Posted: 1/28/2018 9:37:06 AM EDT

[#5]

Thunder Tactical upper

This is the upper I have.

I've been Youtubing and Googling this, and it seems like .308 AR's tend to have issues with being overgassed. I may see about getting an adjustable gas block to see if it helps.

I'd say out of the 50 or so rounds I put through it, it either stovepiped or did the reverse case thing about 15 or 20 times.

I'll try to post some more pictures of the bolt and extractor later.

Posted: 1/28/2018 9:45:23 AM EDT

[#6]

If you could answer some of the other questions here we might find something.

I would say a 7.62 18" midlength upper is definitely going to be overgassed with 308 ammo. I have adjustable gas blocks on my 308 uppers. With the amount I close them down to optimize my brass placement I can't imagine not having them.

-Stooxie

Posted: 1/28/2018 11:08:21 AM EDT

[#7]

I was also going to suggest overgassed...

Get an adjustable gas block. Seeking makes a decent one at a decent price.

Posted: 1/28/2018 12:08:59 PM EDT

[#8]

either stovepiped or did the reverse case

View Quote

My 223 AR did that, I reduced the gas by moving the gas block forward to blind some gas port and fixed it. If you reload, you can experiment with powder charge and determine if gas related.

Posted: 1/28/2018 5:32:57 PM EDT

[#9]

Overgassed, by the shear volume of .308 sized powder charge weights / cyclic speed is overwhelming the other parts ability to keep up.

( not necessarily just by the pressure, but the amount / volume of that pressure... garden hose v. firehose thing... both have the same water pressure, just different volumes of water. )

You can imagine how fast the action is working because of your comment..."Several times the empty case itself was turned completely backwards in the chamber, causing it to jam. "
Heck, it is running so fast that a case can't even get out of its own way... Lol.

Adjustable GB first... ( buy a spare gas tube and gas tube pin with it ) different buffer weights and recoil springs later to fine tune if desired.

You can calm down the violent cyclic speed dramatically.... easier on the parts, easier to stay on target, easier on the brass....

Trust me... you'll like it.

Posted: 1/29/2018 1:44:27 AM EDT

[#10]

Here are some photos of the bolt. Granted, my photography skills are shit and I haven't had time to clean it yet, but here are the pics:

Attached File

Posted: 1/29/2018 3:20:15 AM EDT

[#11]

Quote History

Quoted:
OP, love the avatar, btw. Roy Fokker's VF-1s. Brings back the memories.

-Stooxie

View Quote

Hell yeah!

I spent many afternoons racing home after school to catch the latest episode.

Posted: 1/29/2018 9:35:16 PM EDT

[#12]

#1. Check your gas block alignment. If the gas port is partially blocked because the gas block isn't lined up properly you will get this problem.

#2. Your bolt and carrier look bone dry. Lube it liberally with your favorite brand of oil. It should look wet.

#3. Clean that bolt face up with a tooth brush and plenty of solvent. It looks rough for a new bolt.

#4. If you use reloads get a quality gage and bump the shoulder at least -.003" to -.004" shorter than the fired measurement. Before loading a bunch, make sure they feed and cycle without binding.

I'm running Slash's heavy buffers. Never had a malfunction yet, but haven't shot them a bunch either. Noveske barrels and Armalite parts in mine.

Posted: 1/31/2018 3:14:41 PM EDT

[#13]

Quoted:
I recently put together a .308 (Thunder Tactical upper with an 18" bbl) and I'm having trouble with extraction / ejection. The first time I took it out I used some cheap Wolf steel case (I know, I know, but I'm poor and it's what I had on hand) and put about 30 rounds through it. It failed to extract multiple times, leaving me to have to pry the case out of the chamber with my fingernail.

Today, I took it out again and put some much nicer nickel plated ammo through it. This time, instead of just flat failing to extract, it would fail to eject the case. Several times the empty case itself was turned completely backwards in the chamber, causing it to jam. Several other times it would stovepipe. I was lucky to get five rounds through it before it would fail to eject. I tried several different mags but I only had one type of ammo (can't remember what it is off the top of my head, but it's nice and nickel plated). I think I put about 50 rounds through it.

Here is a photo of a backwards case stuck in the chamber:

https://www.AR15.Com/media/mediaFiles/6032/FTE-433621.JPG

Suggestions? New extractor, maybe, or is it just having teething problems?

View Quote

OP, I have the same upper from Thunder Tactical, but haven't had any issues. Been through about 100 rounds of Hirtenberger surplus ammmo.

Posted: 1/31/2018 6:06:41 PM EDT

[#14]

Quote History

Quoted:

OP, I have the same upper from Thunder Tactical, but haven't had any issues. Been through about 100 rounds of Hirtenberger surplus ammmo.

View Quote

The overgas starts to show after some shooting when carbon seals gas block leak. Takes 100-200 rnds. My 223 AR and 308 AR were around 100-150 rnds.

Posted: 1/31/2018 7:26:06 PM EDT

[#15]

I actually start new builds on wolf.

Posted: 2/1/2018 7:56:17 AM EDT

[#16]

I just ordered a JP Enterprises adjustable gas block from Midway. Hopefully, it will tame the problem.

Posted: 2/1/2018 10:52:57 AM EDT

[#17]

Quote History

Quoted:
#1. Check your gas block alignment. If the gas port is partially blocked because the gas block isn't lined up properly you will get this problem.

#2. Your bolt and carrier look bone dry. Lube it liberally with your favorite brand of oil. It should look wet.

#3. Clean that bolt face up with a tooth brush and plenty of solvent. It looks rough for a new bolt.

#4. If you use reloads get a quality gage and bump the shoulder at least -.003" to -.004" shorter than the fired measurement. Before loading a bunch, make sure they feed and cycle without binding.

I'm running Slash's heavy buffers. Never had a malfunction yet, but haven't shot them a bunch either. Noveske barrels and Armalite parts in mine.

View Quote

Yep. Exactly what borderpatrol suggested. Try working the bolt back and forth 100+ times or more to break-in the rifle. Run it wet, especially when new.

Posted: 2/19/2018 8:04:48 AM EDT

[#18]

I tested out the adjustable gas block yesterday. Took four rounds to get it dialed in. I didn't have much time to shoot, so I ended up putting about 40 rounds through it. Had one stovepipe, but it ran quite nicely otherwise.

Attached File

Posted: 2/19/2018 11:47:50 AM EDT

[#19]

What ammo still stove piped ?

Steel cased isn't as springy as brass cased so extraction can still be an issue.

Posted: 2/19/2018 9:46:42 PM EDT

[#20]

Did you ever remove the extractor to see if it had 2 o-rings?

Posted: 2/19/2018 10:28:47 PM EDT

[#21]

Quote History

Quoted:
What ammo still stove piped ?

Steel cased isn't as springy as brass cased so extraction can still be an issue.

View Quote

I don't remember the brand, but it was some pretty nice nickel-plated stuff I picked up several years ago. I think the gas port set screw may have moved a bit, since I didn't have any loctite with me at the time. It only did it once, and I tweaked the set screw once it happened and I didn't have any more stove pipes.

Posted: 2/21/2018 11:51:27 AM EDT

[#22]

Quote History

Quoted:

I don't remember the brand, but it was some pretty nice nickel-plated stuff I picked up several years ago. I think the gas port set screw may have moved a bit, since I didn't have any loctite with me at the time. It only did it once, and I tweaked the set screw once it happened and I didn't have any more stove pipes.

View Quote

Excellent.

Posted: 2/22/2018 10:21:36 PM EDT

[#23]

Quote History

Quoted:
#1. Check your gas block alignment. If the gas port is partially blocked because the gas block isn't lined up properly you will get this problem.

#2. Your bolt and carrier look bone dry. Lube it liberally with your favorite brand of oil. It should look wet.

#3. Clean that bolt face up with a tooth brush and plenty of solvent. It looks rough for a new bolt.

#4. If you use reloads get a quality gage and bump the shoulder at least -.003" to -.004" shorter than the fired measurement. Before loading a bunch, make sure they feed and cycle without binding.

I'm running Slash's heavy buffers. Never had a malfunction yet, but haven't shot them a bunch either. Noveske barrels and Armalite parts in mine.

View Quote

Same, except I went with the CTS Aktiv buffers. Much cheaper, very impressive results.

Posted: 2/23/2018 9:20:12 PM EDT

[#24]

I have to say I've learned a lot in a short time on this site. So am I correct to assume that a 16 inch barrel is better suited to a mid length gas system than an 18 inch? I had no idea how important the gas system length was.

Posted: 2/23/2018 10:57:20 PM EDT

[#25]

The extractor is slipping off the rim of the case. The gas pressure exaggerates the problem but is not the root cause. A JP or DPMS G2 extractor will solve the problem. AR308 extractors are poorly designed and this manufacturer probably sources them from one of the few BCG makers.

[ARCHIVED THREAD] - Failure to eject - .308 18" barrel

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