Brass stays in chamber - Page 2

Handler62 · July 9, 2018, 06:52 AM

No backed out primers dinner the first range session and no damage to the rim.
In my mind, the lack of damage to the rim rules out to setting of an extractor, but I'm obviously noi expert. I would buy your logic on to strong of an extractor not allowing full lockup and thus not grabbing the case good. It's just wired that it ejects when the rifle short strokes but not when it fully locks open.
I know what you mean about "net guessing". I troubleshoot welder generators over the phone and internet for a living so i know your only as good as the information provided and I appreciate the help everyone is providing.

stagpanther · July 9, 2018, 07:35 AM

Are you getting any round ejector imprints on the rim face?

ed308 · July 9, 2018, 08:20 PM

Check the lip of the extractor. I had a junk extractor get progressively worse with time. And there's been some bad extractors sold the last couple of years. Check the ejector and tension on the extractor as well. If you've got a spare bolt, try it with the other bolt. If it happens with both bolts, that rules out a problem with the bolt, ejector and extractor.

riffraff · July 9, 2018, 09:08 PM

I think if I was still trying to figure something like this out I'd be swallowing my pride and dropping it off at a local gunsmith.

Handler62 · September 4, 2018, 05:20 PM

Anyone know where I can get a rifle length pig tail or spiral gas tube? Local gun shop owner is doing this on Aero rifles to fix this exact issue but can't find any in rifle length. I hope to finally get back on this project soon!

marine6680 · September 4, 2018, 07:25 PM

You shouldn't need anything like that.

First... Double check your buffer spring is the correct one.

An adjustable gas block should not be so sensitive as to go from under to over in a small fraction of a turn.

Some AR10 based rifles use the same buffer and spring system as a 5.56, others do not. Be 100% sure about both parts.

Possible bad barrel, and a possible bad gas block.

Possible that the bolt is at fault. A bad extractor can cause this. Talk of difficulty in closing the bolt sometimes... Makes me wonder if the extractor is not snapping around the rim properly.

Check your brass... If the brass stays in the chamber and the extractor is forced to slip off of it, you will see damage on the case rim. Pay attention to how the damage is shaped and in what direction it goes. An extractor that slips will pull backward, and an extractor that is not snapping around the case properly will leave damage pushing forward.

There should be no need for tungsten in the buffer with an adjustable gas block.

After confirming your parts, you may want to see about a replacement gas block or barrel.

Handler62 · September 5, 2018, 05:27 AM

Buffer assembly is all 308 stuff, no 223 parts mixed in. Tungsten weights are already out. I confirmed with the internet that he had already used this fix successfully and everything makes sense.
The gas is getting to the bolt to fast so a longer tube will delay the pressure pulse long enough for the chamber pressure to drop low enough to release to brass. There's nothing wrong with the brass, I tried multiple brands, all factory loads, besides the brass comes out no problem by hand cycling the rifle after, which points to too high of chamber pressure at the time of extraction. The band out primers would also point to high chamber pressure when the bolt is starting to move.

Mobuck · September 5, 2018, 05:53 AM

So, here's a thought: If the chamber is "tight" and the bolt isn't fully going into battery (but enough to fire), the extractor isn't getting a good purchase on the rim. When fired, it takes only a little gas to unlock the only partially engaged bolt lugs and the bolt cycles but the extractor slips off w/o really marking up the rims.
An 18" barrel with rifle gas is barely functional on a .223 but I don't know much about the 6.5.

stagpanther · September 5, 2018, 06:28 AM

Dwell timing by itself should not create an over-pressure situation.

You have described a lot of stuff verbally--but you hurt your cause by posting no pictures at all.

Based on what I can decipher--you have something creating an over-pressure on cartridge ignition. Brass tells the story--have a reloader or your GS check your spent cases--I'm guessing even without looking at it you've got some expansion/flow in the cases that failed to extract.

marine6680 · September 5, 2018, 07:08 PM

Mobuck is following my line of thinking.

If the rifle is over gassed and the bolt is cycling with the brass staying stuck in the chamber...

There WILL be damage to the case rim.

If there is no damage to the case rim... Your bolt is not fully locking into place, and the extractor is not holding onto the case rim, so it simply can not extract the case.

Or it could be a broken extractor... But I doubt that, as it seems to work sometimes... But possible I guess.

bfoosh006 · September 12, 2018, 03:39 PM

IMHO... the buffer weight should be fine.

5.4oz buffer weights are the norm. in a .308 sized AR.

BUT....

I am thinking the chamber pressure is to high when the case is trying to be extracted.

Are you sure the GB is aligned properly ? If it is "off" ( not centered over the gas port ) that might be the reason for the weird adjustment results.

Ultimately... the chamber pressure needs to be allowed to drop more... so slowing down the BCG movement will allow that.

I'd try a heavier recoil spring weight, and heavier buffer weight ( at the very least put the Tungsten weights back in ) ... and then after being positive the Adj. GB is centered over the gas port.... adjust again.

I currently run a 9.3oz rifle length buffer and a Tubbs .308 Flatwire recoil spring with my SLR adj. GB opened ( from closed ) 6 of 15 available clicks.

All of my Large Frame AR's run 100% like I have listed. .308 6.5CM various barrel lengths and gas lengths... carbine 12.5 barrel, middies and rifle lengths up to 22".. etc
Carbine stocked run a 5.4oz buffer weight, rifle length is the 9.3oz buffer.

I suspect the backed out primers are just from the BCG moving rearward, without supporting the case head / primer pocket. ( IE the chamber pressure to high and the extractor is "popping" off the case rim...and allowing primer movement. That pressure needs to go some where )

So ... KAK sells the heavy 9.3oz .308 rifle length buffer, and the Tubbs is cheapest at LaRues.

I also still wonder about the abrupt GB results... so double check the GB alignment. JP makes good stuff. And ( no offense ) be sure to snug up the "locking screw" after the adjustments... every time, just in case that is somehow messing with the results.

July 9, 2018, 07:35 AM	#27
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,775	Are you getting any round ejector imprints on the rim face? __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

July 9, 2018, 08:20 PM	#28
ed308 Senior Member Join Date: November 5, 2016 Location: DFW, TX Posts: 1,147	Check the lip of the extractor. I had a junk extractor get progressively worse with time. And there's been some bad extractors sold the last couple of years. Check the ejector and tension on the extractor as well. If you've got a spare bolt, try it with the other bolt. If it happens with both bolts, that rules out a problem with the bolt, ejector and extractor. Last edited by ed308; July 10, 2018 at 08:44 AM.

September 5, 2018, 06:28 AM	#34
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,775	Dwell timing by itself should not create an over-pressure situation. You have described a lot of stuff verbally--but you hurt your cause by posting no pictures at all. Based on what I can decipher--you have something creating an over-pressure on cartridge ignition. Brass tells the story--have a reloader or your GS check your spent cases--I'm guessing even without looking at it you've got some expansion/flow in the cases that failed to extract. __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

September 12, 2018, 03:39 PM	#36
bfoosh006 Senior Member Join Date: February 17, 2009 Posts: 1,089	IMHO... the buffer weight should be fine. 5.4oz buffer weights are the norm. in a .308 sized AR. BUT.... I am thinking the chamber pressure is to high when the case is trying to be extracted. Are you sure the GB is aligned properly ? If it is "off" ( not centered over the gas port ) that might be the reason for the weird adjustment results. Ultimately... the chamber pressure needs to be allowed to drop more... so slowing down the BCG movement will allow that. I'd try a heavier recoil spring weight, and heavier buffer weight ( at the very least put the Tungsten weights back in ) ... and then after being positive the Adj. GB is centered over the gas port.... adjust again. I currently run a 9.3oz rifle length buffer and a Tubbs .308 Flatwire recoil spring with my SLR adj. GB opened ( from closed ) 6 of 15 available clicks. All of my Large Frame AR's run 100% like I have listed. .308 6.5CM various barrel lengths and gas lengths... carbine 12.5 barrel, middies and rifle lengths up to 22".. etc Carbine stocked run a 5.4oz buffer weight, rifle length is the 9.3oz buffer. I suspect the backed out primers are just from the BCG moving rearward, without supporting the case head / primer pocket. ( IE the chamber pressure to high and the extractor is "popping" off the case rim...and allowing primer movement. That pressure needs to go some where ) So ... KAK sells the heavy 9.3oz .308 rifle length buffer, and the Tubbs is cheapest at LaRues. I also still wonder about the abrupt GB results... so double check the GB alignment. JP makes good stuff. And ( no offense ) be sure to snug up the "locking screw" after the adjustments... every time, just in case that is somehow messing with the results. Last edited by bfoosh006; September 12, 2018 at 03:50 PM.

July 9, 2018, 06:52 AM	#26
Handler62 Junior Member Join Date: June 9, 2018 Posts: 13	No backed out primers dinner the first range session and no damage to the rim. In my mind, the lack of damage to the rim rules out to setting of an extractor, but I'm obviously noi expert. I would buy your logic on to strong of an extractor not allowing full lockup and thus not grabbing the case good. It's just wired that it ejects when the rifle short strokes but not when it fully locks open. I know what you mean about "net guessing". I troubleshoot welder generators over the phone and internet for a living so i know your only as good as the information provided and I appreciate the help everyone is providing.

July 9, 2018, 09:08 PM	#29
riffraff Senior Member Join Date: January 21, 2016 Posts: 629	I think if I was still trying to figure something like this out I'd be swallowing my pride and dropping it off at a local gunsmith.

September 4, 2018, 05:20 PM	#30
Handler62 Junior Member Join Date: June 9, 2018 Posts: 13	Anyone know where I can get a rifle length pig tail or spiral gas tube? Local gun shop owner is doing this on Aero rifles to fix this exact issue but can't find any in rifle length. I hope to finally get back on this project soon!

September 4, 2018, 07:25 PM	#31
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	You shouldn't need anything like that. First... Double check your buffer spring is the correct one. An adjustable gas block should not be so sensitive as to go from under to over in a small fraction of a turn. Some AR10 based rifles use the same buffer and spring system as a 5.56, others do not. Be 100% sure about both parts. Possible bad barrel, and a possible bad gas block. Possible that the bolt is at fault. A bad extractor can cause this. Talk of difficulty in closing the bolt sometimes... Makes me wonder if the extractor is not snapping around the rim properly. Check your brass... If the brass stays in the chamber and the extractor is forced to slip off of it, you will see damage on the case rim. Pay attention to how the damage is shaped and in what direction it goes. An extractor that slips will pull backward, and an extractor that is not snapping around the case properly will leave damage pushing forward. There should be no need for tungsten in the buffer with an adjustable gas block. After confirming your parts, you may want to see about a replacement gas block or barrel.

September 5, 2018, 05:27 AM	#32
Handler62 Junior Member Join Date: June 9, 2018 Posts: 13	Buffer assembly is all 308 stuff, no 223 parts mixed in. Tungsten weights are already out. I confirmed with the internet that he had already used this fix successfully and everything makes sense. The gas is getting to the bolt to fast so a longer tube will delay the pressure pulse long enough for the chamber pressure to drop low enough to release to brass. There's nothing wrong with the brass, I tried multiple brands, all factory loads, besides the brass comes out no problem by hand cycling the rifle after, which points to too high of chamber pressure at the time of extraction. The band out primers would also point to high chamber pressure when the bolt is starting to move.

September 5, 2018, 05:53 AM	#33
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	So, here's a thought: If the chamber is "tight" and the bolt isn't fully going into battery (but enough to fire), the extractor isn't getting a good purchase on the rim. When fired, it takes only a little gas to unlock the only partially engaged bolt lugs and the bolt cycles but the extractor slips off w/o really marking up the rims. An 18" barrel with rifle gas is barely functional on a .223 but I don't know much about the 6.5.

September 5, 2018, 07:08 PM	#35
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	Mobuck is following my line of thinking. If the rifle is over gassed and the bolt is cycling with the brass staying stuck in the chamber... There WILL be damage to the case rim. If there is no damage to the case rim... Your bolt is not fully locking into place, and the extractor is not holding onto the case rim, so it simply can not extract the case. Or it could be a broken extractor... But I doubt that, as it seems to work sometimes... But possible I guess.