Brass stays in chamber

[Handler62]

Had my new 6.5 creedmoor build out yesterday and had an issue of the brass remaining in the chamber. The bolt cycles back and locks open. It has an adjustable gas block which i started closed and worked open until the blot locked. First 4 shots were fine, next 8 the brass did not leave the chamber (all after the gas block was set) . Cycling unfired rounds by hand all works fine. Brass comes out easily with a cleaning rod down the barrel, no pounding required. Extractor seems to grab case fine when bcg is outof the rifle and the ejector moves freely.

2 of the pieces of brass had the primers half out the back of the case.

Comments are: Areo m5e1 receivers and buffer assembly, faxon barrel, Rainer bcg, jp block, spike's tube. Hornaday American whitetail factory ammo.

Any thoughts?

[marine6680]

Over gassed...

A failure to extract means there is an issue with the extractor components, or the system is over gassed and is unlocking before the pressure drops enough in the chamber.

[Nathan]

This strikes me as something you might not be able to get right with the current spring and buffer. So, you might need to go to a heavier buffer and readjust your gas block. I haven’t had this issue before so take this advice with a grain of salt.

[ed308]

Make sure the bolt and bolt carrier is well lube, especially when breaking in the AR. I usually adjust adjustable GB another 1/2 turn after the AR cycles properly. I would also scrub and polish the chamber if the barrel is melonite treated.

2 of the pieces of brass had the primers half out the back of the case.

That might be a separate problem that would concern me more than stuck brass. Factory ammo or your reloads?

[mehavey]

Primers backed out (in this case), extractor has failed/ripped through rim
and bolt face has left the case base while pressure still high.

Since you adjusted the gas from zero until the bolt locked back/full travel
-- slow it down with heavier buffer/spring as a start.

Just for grins and before the spring/buffer change-out... lube the cases
(yes... lube the friggin' case) and let us know the results.*



* (an MEHavey/Slamfire patented technique.)

[Handler62]

Thanks for the advice. I'll try to get out to the range in the next week to try some of this.

It was factory loads. Hornaday American whitetail

Barrel and bcg are both melonite. How would I go about polishing the chamber?

[Mobuck]

"Barrel and bcg are both melonite. How would I go about polishing the chamber?"

IMHO, if you have to ask, you probably shouldn't be doing the job yourself.

[marine6680]

Unless the barrel is cheap junk... Polishing the chamber shouldn't be necessary.

[stagpanther]

Creedmoors are tricky birds to time, I've built several of them but never had an issue with hornady whitetail--other than it has a disturbing habit of making my handloads look bad. Your primers backing out are a bad sign IMO, my back of the napkin guess is your running the pressure up abnormally high somehow.

The whitetail is just an interloc spire point so it should have no problem chambering--but the creedmoor can easily have issues with cartridges making their way into the chamber in good form depending on how precise the barrel extension to bolt aligment is (this can also affect the bolt to extension lock up) as well as proper alignment of the cartridge, especially with high SD bullets seated long (try getting a berger vld seated long to chamber without issues--it's a major challenge). The "pitch angle" of the cartridge in the magazine can also influence whether or not the cartridge makes it in undamaged--I've used magazines where the meplat of the bullet would smack into the chamber face rim on the way into the chamber--this can do numerous bad things to your cartridge.

What is the length of your barrel and what gas system length? A gun can be overgassed and still work--I'm thinking you could have a dwell timing issue but if that were the case you would almost certainly see damage to the case rim by the extractor failing to pull the case.

If I were you, I would take the upper apart and reassemble it--I have a PTG receiver lapping tool for 308 but they no longer make them regular production--but will still make you one custom order. I would reassemble making as sure as you can that you have a trued collar to extension mate--and that the "bore" of the upper is true. Two commercial uppers of mine were not true in the inside of the receiver--though that was easy to polish in (often it's a mater of the inside receiver being coated with cerkote or other "substances") Obviously you want to make sure your headspace is in compliance (using whatever method your comfortable with). I've had a creedmoor build that was giving me no end to troubles--but after I took it apart and put it back together as precisely as I could the troubles mysteriously vanished. Just my wild net-guesses.

[Mobuck]

I saw some pics of fired 6.5 Crud(oops Creed)more brass that appeared to have been extracted, dropped in the ejection port, and then slammed against the barrel extension by the returning bolt. Shoulders crumpled, case mouth bent/mangled---no way that happened in the chamber.
There's a lot of things happening inside the receiver in a very short time after the round is fired.

[ed308]

This is what I've done with sticky AR chambers...

I use a .410 shotgun cotton swab that I coat with Fitz metal polish. Mount the swab on a short cleaning rod and turn with a drill. The key is to not to stay in any one place too long. Keep the swab moving back and forth. It won't take much to get a mirror finish. Then clean the chamber and barrel thoroughly. Don't lube the chamber. Keep it clean and dry.

This has cured many sticky and tight AR chambers over the years. I like melonite treated barrels. But the process can leave junk in the chamber.

Keep an eye on the primers with that ammo. I doubt you have a headspace problem since all new parts. I've never checked headspace on any AR I've built. But this case with primers backing out and brass sticking, not a bad idea since the AR is showing signs of high pressure. But it wouldn't surprise me to hear the problem goes away after polishing/cleaning the chamber.

[bfoosh006]

What gas length are you using ? ... it does matter quite a bit.

A middie will try to yank the spent cartridges out at much higher pressures then a rifle length gas system.

And as for honing the chamber... first make sure it is very clean.

It is possible that there is "shipping oil / preservative" that is getting "gummy" after you heat up the chamber.


I hone my chambers with a .308 chamber brush, lightly wrapped in 0000 Steel wool... ( won't even scratch glass ) and your favorite solvent.

Spun on a section of cleaning USGI cleaning rod Via a cordless drill.

BE SURE to clean out all the "fuzz" left over from the 0000 Steel Wool ...PRIOR to seating the bolt !!!!!
It will lock up super tight from those fine steel wool particles !!!

Blow it out with a can of compressed air and thoroughly clean the chamber of the fuzz.

If it isn't very clean of the fuzz.. you'll be the first to know.

That said... I do it to all my large frame AR's... and I also polish the feed ramps and sharp edges on the feed lugs.

[Handler62]

-update-
Got back out to the range today after I cleaned, but did not polish, the chamber. Also swapped out 3 of the 6 buffer weights with tungsten in the hopes it would open up the window of adjustment on the gas block.
First time out I went from under glassed to over gassed in a matter of a 1/4 turn. This time I worked the gas block open until all functioned properly, then gave it another 1/4 turn for variance in ammo. Well that extra 1/4 turn put me right back to over gassed, round stuck in the chamber.
I'm going to try polishing the chamber but should I be looking at a heavier buffer spring? Or add more weight to the buffer?
Interesting observation made by my buddy picking up my brass, rounds that did not fully cycle the gun (while working the gas block open) were not even warm right out of the gun, but once the action was working you couldn't touch the brass for several minutes it was so hot. Still shooting all factory hornaday American white tail ammo.

[stagpanther]

I went from under glassed to over gassed in a matter of a 1/4 turn

Probably not.

Still don't know what your barrel and gas system length is.

[Handler62]

Barrel is 20 inch faxon, rifle length gas system. Buffer assembly is aero 308 rifle

[LineStretcher]

Did you just pick a bolt at random or is it matched to the barrel? You should be using a H2 buffer. Is the gas key loose?

First, stop firing this rifle, you obviously have serious issues with it.

1. Get a H2 buffer with the correct spring for your buffer tube.
2. Get a set of head space gauges and check the head space.
3. Check the gas key. If its loose fix that.
4. Check gas tube and gas key alignment.

[stagpanther]

Barrel is 20 inch faxon, rifle length gas system. Buffer assembly is aero 308 rifle

Sounds like a pretty well-balanced set-up to me shouldn't be any outstanding gas or dwell timing issues that couldn't/shouldn't be easily tuned out--unless maybe the gas port in the barrel is over-sized (which is pretty rare).

It's also fairly common that 308 bolts are "over-powered" these days--meaning that both the extractor and ejectors are very heavily sprung--and can cause these kinds of issues. I just bought a bolt for my 338 fed build which suffers exactly these problem, though fairly easily fixed by tuning down the springs and polishing the edge of the extractor and ejector.

[CarJunkieLS1]

I agree with above posts. There is no way it went from under/over gassed in 1/4 turn of your gas block. Put an H2 buffer in it and check your bolt and make sure that your extractor is like it should be.

[Handler62]

With 3 tungsten weights it's already an h3 buffer. I just checked my build notes and it's actually an 18in bbl not a 20 but it is a rifle length gas system.

Bolt was head space checked at my local gun shop where I purchased the bcg. He said it was tight but in spec, just barely closed on the go gauge.

[stagpanther]

He said it was tight but in spec, just barely closed on the go gauge.

It either closes or it doesn't. Reading between the lines here--does he mean he had to use more than normal force to overcome a resistance to closing? I think this needs closer attention. Some force is needed to get the bolt to turn and engage the extension, but notably excessive resistance to a cartridge going into battery or extracting is not good. Take a look at your bolt and extension lugs--if it's relatively new and coated with something--you might be able to see signs of unusual wear. Is your bolt face pitted? I'm not a big fan of "masking" unbalanced gas systems by playing musical chairs with springs, buffers etc. They may work for a while--but eventually the underlying problem will manifest itself in some other way.

[LineStretcher]

Originally Posted by Handler62

With 3 tungsten weights it's already an h3 buffer. I just checked my build notes and it's actually an 18in bbl not a 20 but it is a rifle length gas system.

Bolt was head space checked at my local gun shop where I purchased the bcg. He said it was tight but in spec, just barely closed on the go gauge.

H3 is too much. It might be ok if you were using a non adjustable gas block. H2 will be easier on your shoulder too.

Go means that the bolt should close easily, no go means it does not close. With the go gauge you should be able to hold the barrel and upper vertically and drop the bcg and bolt in from about 3 inches out and it should lock in place with the BCG being near flush with the back of the receiver. Applying a little pressure to get it locked is acceptable but a hard push is not.

If you cant do that you may either have a headspace problem or a BCG problem.

[Handler62]

I wasn't present for the head space check so I'm not sure on the amount of force needed. I do know this guy builds multiple AR's a week and knows what he is doing. He also had multiple bcg's on hand so if the first one didn't work there would be no reason not to just move on to the next one. Basically head space is the variable I am least concerned with for this gun.

I agree with what was said before that there is no way I should be going from under to over gassed this fast and the must be something else going on here.

I like all the fefeed back and advice guys, keep it coming and I'll keep you up to date, hope to shoot again this weekend.

[stagpanther]

Hornady's commercial ammo is generally engineered to achieve optimal performance while staying well below max pressure ratings.

I put a creedmoor together once that was having all kinds of problems--all the "usual suspects" checked out and I was stumped. The creedmoor cartridge can be a difficult one to cycle and chamber properly because the cartridge may not get the necessary lift from the ramp prior to getting to the chamber face--in this way it's similar to the Grendel. I took the upper apart and reassembled it and it was a new gun and ran without a problem--the only conclusion I came to was that even slight .001 or less misalignment of the bolt to extension was enough to cause my problems. The creedmoor does not need heavy springs or buffers if it's gassed right IMO.

[Handler62]

Range trip number 3 today. Cleaned and light polish on the chamber. By light I mean I used some mother's mag and aluminum polish on a 410 mop. Put it on the drill for between 1 and 2 minutes. Took one of the tungsten weights out of the buffer as well so it's an "h2" now. Also picked up some American eagle 120gr jhp just to try something different.
Started with the gas block closed again, was about 2 full turns open and the bolt was short stroking but was throwing the brass. Another half turn and the bolt was locking open but one again the brass was left in the chamber. Was able to close the bolt and hand cycle the empties out without any unusual amount of force.
I'm starting to think there might be an extractor issue. Maybe damaged something last time when the brass was much harder to get out of the chamber?
I'm planning to take this in to my local gun shop where I bought the bcg and have him take a look.
If nothing comes of that I may try the disassemble and reassemble off the upper.

[stagpanther]

I'm pretty sure I could figure it out--if I had the gun in hand. Otherwise I'm just net-guessing; but here's my current thinking. If you had too short dwell time and the bolt tried to extract the case before it had relaxed--you would likely see a gash on the side of the rim as the extractor failed to get a good enough grip. I've had a few bolts with overpowered ejectors and extractors--if your BCG isn't engaging with enough momentum--the "resistance" of the ejector/extractor could be enough to prevent the "grabbing" of the rim--and this could also possibly explain creating a less than perfect lock of the bolt to the extension, which in turn might create extra headspace--which concievably could result in the backed-out primers you previously mentioned. Just wild guesses.

Brass almost always tells the story of what's going on in the gun.