AR 10 not ejecting spent case

jd.caldderon · July 4, 2015, 10:24 AM

Question if any of you have run into this? I built an AR 10 in .243 and it's been running great. I took it out yesterday and fired about 60 rounds through it. Not quickly just target shooting. The last two rounds however failed to eject and the next misfeed., but you could pull the charging handle and it would then eject. Question is has anyone ran into this? just wondering if .243 dumps so much gas back into the action it fouls that much faster. Thanks.

**44 AMP** · July 4, 2015, 11:12 AM

The operation of any gas operated auto is a balancing act between the amount of gas in the bore (port pressure) and how much is tapped off to work the action while the pressure is available (pressure curve), and at the right time in the pressure curve to allow the action to function correctly.

Moving to Semi Auto rifle forum, where you should find some help...

Theohazard · July 4, 2015, 11:30 AM

Usually if an AR-type rifle leaves empty brass in the chamber that means it's over-gassed; the bolt is unlocking too quickly and the rifle is trying to extract the case while the pressure is still too high. This means the case is still expanded and sealed to the chamber during the extraction process, so sometimes the extractor can't pull it out and the extractor claw slips over the case rim and the empty stays in the chamber.

The most common fix for this is a heavier buffer, which will slow down the bolt unlocking and allow the pressure to drop before the extractor tries to pull the case out of the chamber. It also wouldn't hurt to check that the chamber isn't excessively fouled and that the extractor isn't weak, because those can contribute to the problem.

jd.caldderon · July 4, 2015, 12:14 PM

Thanks, I'm going to clean it up and see if it will run flawless like it did before. If not I'll try the buffer, then the extractor.

Palmetto-Pride · July 5, 2015, 09:36 AM

Could be your gas block has slipped forward a little and now the port in the barrel and the gas block have become misaligned that would cause a under gas short stroking situation. That happened to my M&P10 its a easy fix just realign it.

marine6680 · July 5, 2015, 04:20 PM

Check that it isn't short stroking.

If the gas block slipped, then less gas enters the action.

If you short stroke enough, it will appear like the case didn't extract, when in fact the case never cleared the chamber during the movement of the action, and was pushed back into the chamber.

That isn't the most likely short stroke scenario, but possible on a severe short stroke issue.

It could be that the carrier didn't move at all due to not getting any gas. You will feel the recoil but the action will not move.

Misfeeds can be caused by short stroking as well.

But if the case is staying in the chamber, and the next round is trying to feed in behind it, then that is a failure to extract, and is a symptom of over gassed.

I know 308 ARs like to have less dwell time than a 5.56 AR. On 18in barrels a rifle length gas system works well with them, while that is a little on the short side of dwell time on a 5.56.

This may also be the case for your AR... A heavier buffer can help.

jd.caldderon · July 5, 2015, 08:33 PM

Thanks for the input everyone. I'll do some tinkering with it and see about a heavier buffer.

skizzums · July 5, 2015, 08:50 PM

this has happened to me once, and it was the gas block having slipped out of alignment.

an easy way to align is to remove the block, stick a toothppick into barrel port and break it off flush. then put gas block back on barrel, turn upside down until the tothpick can fall into the block. then tighten block and remove toothpick with a cleaning rod or whatever. if your port is much bigger than the toothpick, you may need to find something else that closer in size to the port. if you dont like the idea of breaking the toothpick out of the barrel, then get it aligned, make several alignment marks with a sharpie, then remove object from port and reinstall block using the marks.

jd.caldderon · July 5, 2015, 09:30 PM

Do you guys think an adjustable gas block would solve the issue if it's and over pressure issue? Skizzums I'll try your idea first.

skizzums · July 5, 2015, 10:04 PM

it probably coould. but you said it worked fine before, so what changed? ammo? or something with the rifle? if everything is the same and it just quit working properly, then the issue can be solved without retuning gas system

is it ejecting some of the time but not all of the time? if so, then yes you should contemplate tuning your rifle. but if it's just now not ejecting any of the cases, then you have something else going on

jd.caldderon · July 5, 2015, 10:21 PM

After I built it I tested a variety of ammo through it and have only been running Hornady 95 grain Super Performance SSTs. Right now it has about 100 rounds through it. It ran perfectly until the last 4 rounds I attempted to run after I let it sit for about 2 hours this past weekend. It would fire the round but not eject it. The bolt moved far enough back to pick up the next round and try to chamber it. Just wondering if it's broken in now that's why there may be an over pressure issue.

skizzums · July 5, 2015, 10:44 PM

okay, well if the bolt went back and pick up the next round, then you have an extraction issue.

first, check the extractor. hand cycle the rifle and make sure it's extracting. if it's not the extractor, then you very well may be over gassed. cycle it by hand first and then let us know.

jd.caldderon · July 5, 2015, 11:07 PM

Yup it extracts bye hand when you work the charging handle. I've seen the two ways to fix over pressure is a heavier buffer or an adjustable gas block. Unless there are other methods out there I am unaware of...

A pause for the COZ · July 6, 2015, 12:48 AM

I had a slight issue with mine for a bit. Carbon build up in the ejector.
Cleaned the ejector good and she is working good.

I have actually had that problem more than one in my AR15's too.
Upgraded to a heavier spring in the ejector fixed them.

Quote:

okay, well if the bolt went back and pick up the next round, then you have an extraction issue.

Thats what mine was doing. Stove piping the next round.

marine6680 · July 6, 2015, 01:00 AM

Check the extractor, try a heavy extractor spring, and maybe even the o-ring too.

Look at your brass on the rounds that did eject. Look at the back of the case, on the head stamp... Look and see if there are any smears/swipe marks.

Swipes on the brass is a sure sign of over gassed. It means the bolt is turning to unlock, while there is still pressure in the barrel, and the case is sealed tightly in the chamber and pushing against the bolt.

My AR10 is still doing this a little so I need to go up more on my buffer weight. I would prefer to not need an adjustable gas block, but it may become necessary if adding weight to the buffer does not help.

jd.caldderon · July 6, 2015, 04:14 PM

Ok ordered a new adjustable gas block. I'll let you all know how it goes in case any of you run into an issue. Thanks for the ideas, I was stumped until I heard "over pressure".

Palmetto-Pride · July 6, 2015, 07:28 PM

Quote:

Right now it has about 100 rounds through it. It ran perfectly until the last 4 rounds

I just don't see how a over pressure/gas issue could start on the last 4 rounds after running fine for 96 rounds. Have you considered that your chamber may be dirty and just needs cleaning? I would run a chamber brush through it and see what happens.

jd.caldderon · July 6, 2015, 08:12 PM

I thought that, I hope it's honestly an over pressure issue because it only had 30 rounds down it since the last cleaning. I would want it to run longer dirty than 30 rounds lol.

Theohazard · July 7, 2015, 01:06 AM

Quote:

Originally Posted by Palmetto-Pride

I just don't see how a over pressure/gas issue could start on the last 4 rounds after running fine for 96 rounds.

An over-gassed rifle leaves empties in the chamber because the brass is still expanded and stuck to the chamber walls when the rifle tries to extract the empty case. And the problem can be worse when the chamber walls are dirty.

My guess is that the chamber walls were clean and smooth enough at first that the rifle still extracted properly because it wasn't too over-gassed. But after the chamber got a little dirty it might have reached the threshold where the empties got stuck in the chamber.

jd.caldderon · July 15, 2015, 03:08 PM

Just a quick update, cleaned the hell out of the rifle (especially) where the round seats in the barrel. Just tested with 30 rounds with various ammo and it and it ran perfectly. Going to go ahead and replace the gas block with an adjustable one so it shld solve the over gassing issue all together.

July 4, 2015, 10:24 AM	#1
jd.caldderon Member Join Date: June 3, 2015 Posts: 21	AR 10 not ejecting spent case Question if any of you have run into this? I built an AR 10 in .243 and it's been running great. I took it out yesterday and fired about 60 rounds through it. Not quickly just target shooting. The last two rounds however failed to eject and the next misfeed., but you could pull the charging handle and it would then eject. Question is has anyone ran into this? just wondering if .243 dumps so much gas back into the action it fouls that much faster. Thanks.

July 4, 2015, 11:12 AM	#2
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,832	Welcome to TFL! The operation of any gas operated auto is a balancing act between the amount of gas in the bore (port pressure) and how much is tapped off to work the action while the pressure is available (pressure curve), and at the right time in the pressure curve to allow the action to function correctly. Moving to Semi Auto rifle forum, where you should find some help... __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

July 4, 2015, 11:30 AM	#3
Theohazard Senior Member Join Date: April 19, 2012 Location: Western PA Posts: 3,829	Usually if an AR-type rifle leaves empty brass in the chamber that means it's over-gassed; the bolt is unlocking too quickly and the rifle is trying to extract the case while the pressure is still too high. This means the case is still expanded and sealed to the chamber during the extraction process, so sometimes the extractor can't pull it out and the extractor claw slips over the case rim and the empty stays in the chamber. The most common fix for this is a heavier buffer, which will slow down the bolt unlocking and allow the pressure to drop before the extractor tries to pull the case out of the chamber. It also wouldn't hurt to check that the chamber isn't excessively fouled and that the extractor isn't weak, because those can contribute to the problem. __________________ 0331: "Accuracy by volume."

July 5, 2015, 09:36 AM	#5
Palmetto-Pride Senior Member Join Date: May 31, 2009 Location: Charleston, SC Posts: 2,071	Could be your gas block has slipped forward a little and now the port in the barrel and the gas block have become misaligned that would cause a under gas short stroking situation. That happened to my M&P10 its a easy fix just realign it. __________________ “The problem with socialism is that you eventually run out of other people's money.” -Margaret Thatcher-

July 5, 2015, 04:20 PM	#6
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	Check that it isn't short stroking. If the gas block slipped, then less gas enters the action. If you short stroke enough, it will appear like the case didn't extract, when in fact the case never cleared the chamber during the movement of the action, and was pushed back into the chamber. That isn't the most likely short stroke scenario, but possible on a severe short stroke issue. It could be that the carrier didn't move at all due to not getting any gas. You will feel the recoil but the action will not move. Misfeeds can be caused by short stroking as well. But if the case is staying in the chamber, and the next round is trying to feed in behind it, then that is a failure to extract, and is a symptom of over gassed. I know 308 ARs like to have less dwell time than a 5.56 AR. On 18in barrels a rifle length gas system works well with them, while that is a little on the short side of dwell time on a 5.56. This may also be the case for your AR... A heavier buffer can help. Last edited by marine6680; July 5, 2015 at 04:25 PM.

July 4, 2015, 12:14 PM	#4
jd.caldderon Member Join Date: June 3, 2015 Posts: 21	Thanks, I'm going to clean it up and see if it will run flawless like it did before. If not I'll try the buffer, then the extractor.

July 5, 2015, 08:33 PM	#7
jd.caldderon Member Join Date: June 3, 2015 Posts: 21	Thanks for the input everyone. I'll do some tinkering with it and see about a heavier buffer.

July 5, 2015, 08:50 PM	#8
skizzums Senior Member Join Date: July 1, 2013 Location: Douglasville, Ga Posts: 4,615	this has happened to me once, and it was the gas block having slipped out of alignment. an easy way to align is to remove the block, stick a toothppick into barrel port and break it off flush. then put gas block back on barrel, turn upside down until the tothpick can fall into the block. then tighten block and remove toothpick with a cleaning rod or whatever. if your port is much bigger than the toothpick, you may need to find something else that closer in size to the port. if you dont like the idea of breaking the toothpick out of the barrel, then get it aligned, make several alignment marks with a sharpie, then remove object from port and reinstall block using the marks. __________________ My head is bloody, but unbowed

July 5, 2015, 09:30 PM	#9
jd.caldderon Member Join Date: June 3, 2015 Posts: 21	Do you guys think an adjustable gas block would solve the issue if it's and over pressure issue? Skizzums I'll try your idea first.

July 5, 2015, 10:04 PM	#10
skizzums Senior Member Join Date: July 1, 2013 Location: Douglasville, Ga Posts: 4,615	it probably coould. but you said it worked fine before, so what changed? ammo? or something with the rifle? if everything is the same and it just quit working properly, then the issue can be solved without retuning gas system is it ejecting some of the time but not all of the time? if so, then yes you should contemplate tuning your rifle. but if it's just now not ejecting any of the cases, then you have something else going on __________________ My head is bloody, but unbowed

July 5, 2015, 10:21 PM	#11
jd.caldderon Member Join Date: June 3, 2015 Posts: 21	After I built it I tested a variety of ammo through it and have only been running Hornady 95 grain Super Performance SSTs. Right now it has about 100 rounds through it. It ran perfectly until the last 4 rounds I attempted to run after I let it sit for about 2 hours this past weekend. It would fire the round but not eject it. The bolt moved far enough back to pick up the next round and try to chamber it. Just wondering if it's broken in now that's why there may be an over pressure issue.

July 5, 2015, 10:44 PM	#12
skizzums Senior Member Join Date: July 1, 2013 Location: Douglasville, Ga Posts: 4,615	okay, well if the bolt went back and pick up the next round, then you have an extraction issue. first, check the extractor. hand cycle the rifle and make sure it's extracting. if it's not the extractor, then you very well may be over gassed. cycle it by hand first and then let us know. __________________ My head is bloody, but unbowed

July 5, 2015, 11:07 PM	#13
jd.caldderon Member Join Date: June 3, 2015 Posts: 21	Yup it extracts bye hand when you work the charging handle. I've seen the two ways to fix over pressure is a heavier buffer or an adjustable gas block. Unless there are other methods out there I am unaware of...

July 6, 2015, 01:00 AM	#15
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	Check the extractor, try a heavy extractor spring, and maybe even the o-ring too. Look at your brass on the rounds that did eject. Look at the back of the case, on the head stamp... Look and see if there are any smears/swipe marks. Swipes on the brass is a sure sign of over gassed. It means the bolt is turning to unlock, while there is still pressure in the barrel, and the case is sealed tightly in the chamber and pushing against the bolt. My AR10 is still doing this a little so I need to go up more on my buffer weight. I would prefer to not need an adjustable gas block, but it may become necessary if adding weight to the buffer does not help.

July 6, 2015, 04:14 PM	#16
jd.caldderon Member Join Date: June 3, 2015 Posts: 21	Ok ordered a new adjustable gas block. I'll let you all know how it goes in case any of you run into an issue. Thanks for the ideas, I was stumped until I heard "over pressure".

July 6, 2015, 08:12 PM	#18
jd.caldderon Member Join Date: June 3, 2015 Posts: 21	I thought that, I hope it's honestly an over pressure issue because it only had 30 rounds down it since the last cleaning. I would want it to run longer dirty than 30 rounds lol.

July 15, 2015, 03:08 PM	#20
jd.caldderon Member Join Date: June 3, 2015 Posts: 21	Just a quick update, cleaned the hell out of the rifle (especially) where the round seats in the barrel. Just tested with 30 rounds with various ammo and it and it ran perfectly. Going to go ahead and replace the gas block with an adjustable one so it shld solve the over gassing issue all together.