barrel length vs gas block location vs port size

[txjm]

I am trying to get a 6x223 running. I know it isn't a 300W but everyone was so much help on my whisper project, I thought I would check in here for answers.
My upper consists of an 18" barrel with the gas block in the carbine position with a .067" port. The caliber is 6x223 or 6x45. I am having problems with the fired cases ejecting. The extractor is jumping over the rim and the bolt is picking up the next case and jamming against the back of the fired case that is in the chamber. I am trying H335 with an 85G SGK. The loads varied from start load to max load(Lee Reloading Manual). All loads had the same issues. I did get a few out of about 15 rounds to eject and pick up the next round properly. The fired cases ejected easily (some of the max loads were a little sticky). The velocity is a little lower than the book values for the min and max loads.
When I chambered the barrel and was playing around with dummy rounds with the ejector removed the extractor seemed easy to snap over the case. Yesterday I compared to another bolt and the other bolt is a little harder to snap over the rim of a case in the chamber.
When I loaded these rounds I worked with the shoulder to rim lenght to minimize headspace. The rounds would chamber out of the mag no problem.
Everything works fine manually.
Where do I go from here? should I have gone with the rifle length port location even though I wanted the block under the handguard? Is my port too large? Is my extractor bad? Is my extractor spring bad? Is my rim to datum case length too long?
Chip

[cav_scout_tj]

First you want fresh extractor parts:
spring, insert, and o-ring.

Like so:
http://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm%20extractor%20spring%20upgrade.htm
You can get them lots of places, but those are the parts you want.

The extractor itself may need replacing too, if its warn, and not getting enough bite.

Start with those parts and see how you do. Clean and polish the chamber too. What brass are you using? Some brass is stickier than others. What does the brass look like? Ripped of rim where extractor was? When my 300 loads get too hot, I get cases stuck in the chamber, but the extractor rips its part of the rim off. Thats pistol port too. Carbine on an 18" should be fine. Not sure about the 0.067... not that familiar with the numbers.

[txjm]

The brass I am using is Speer 07. It has a military crimp and it was real consistent in weight. The rim isn't ripping off but it is leaving a burr when it jumps over it. You can see where a little of the metal is gone on the inside of the rim. It is a new chamber and I think it would benefit from polishing and cleaning. I will try the extractor kit. Does it come with the extractor? Are all extractors the same?

[Colohunter]

Is this a new bolt and extractor, or did it come from a previously used rifle? Having the extractor come of makes it sound like it or it's springs are worn. I would say it isn't just an issue of gas port location as the carrier is moving enough to feed a new round. It could be that the bolt is unlocking while there is still too much pressure, what weight buffer are you using? You might try a heavier one if possible to try to keep the bolt locked in place a little longer.

[MIKEONE]

Whats your load? Ill pop it in quickload to see approx what pressures your running.

Also whose reamer did you use for the chamber?

Mike

[txjm]

"Is this a new bolt and extractor, or did it come from a previously used rifle? Having the extractor come of makes it sound like it or it's springs are worn. I would say it isn't just an issue of gas port location as the carrier is moving enough to feed a new round. It could be that the bolt is unlocking while there is still too much pressure, what weight buffer are you using? You might try a heavier one if possible to try to keep the bolt locked in place a little longer."

All the parts on the upper are new. Most of it is dpms, I think the bolt and carrier group is bushmaster. My buffer is the standard carbine buffer. It does seem that the bolt is unlocking while the case is under too much pressure or the extractor isn't grabbing well. It does work when I manually cycle the action after a jam and the case is still in the chamber. Would a pigtail type gas tube or a fatboy gas tube change anything?

"Whats your load? Ill pop it in quickload to see approx what pressures your running. "

From memory it is a starting load of h335 - 23.5G and a max load of 25.5G. The bullet is a SGK 85G. The oal is max mag. 2.262" Other than OAL I pulled it out of the Lee manual. Maybe the oal is driving the pressure up. I had problems with the starting load doing the same thing. The primer on the starting load looked fine. the max load was a flat.

"Also whose reamer did you use for the chamber?"

The reamer is a PTG.

Thanks Chip

[Colohunter]

The pigtail gas tube could help to delay the ejection a little, though I don't have any experience with those. You an also try an H or H2 buffer to delay the carrier a little bit.

Maybe I missed it, but did you ever mention if you were checking velocity on these loads? If you know velocity numbers that can also show a little more info, especially when checked against the quickload predictions.

[txjm]

The pigtail gas tube could help to delay the ejection a little, though I don't have any experience with those. You an also try an H or H2 buffer to delay the carrier a little bit.

Maybe I missed it, but did you ever mention if you were checking velocity on these loads? If you know velocity numbers that can also show a little more info, especially when checked against the quickload predictions.

The book values start load - 23.5G - 2587 fps and max load - 25.5G - 2818 fps. The oal in the manual is 2.350". My chronograph was messing up and I got one reading at the 24.5G load and the velocity was 2649 fps. That seemed to fall fairly close to the expected. My oal is shorter and I would imagine my 18" barrel is shorter than the Lees test gun.
Thanks Chip

[cav_scout_tj]

I say confirm the extractor parts, if its a new bolt, then the spring and insert should be ok, but an o-ring could help. The o-ring is standard hardware store stuff, 1/4" outside diam, 1/8" inside diam. Slip it over the extractor spring.

Polishing the chamber will help too.

If the whole thing is new, then it probably needs a few rounds to knock the park off the parts. And make sure its WET with oil.

[txjm]

What parts should be wet? bolt and barrel extension?

[cav_scout_tj]

wet: bolt lugs, cam pin area, bolt body inside carrier, a few drops down the carrier key hole. Put a drop in the holes on the side of the carrier. The rails down the carrier bottom and around the key on top.

Basically you could dunk the while bolt carrier group in a quart of oil and that would work fine.

Dont wear a nice shirt when you shoot it. First rounds will blow off any excess.

[txjm]

Whats your load? Ill pop it in quickload to see approx what pressures your running.

Also whose reamer did you use for the chamber?

Mike

I would love to see what you came up with on the H335 loads. 2.262 oal. 85SGK, 23.5G and 25.5G o powder.

Thanks Chip

[txjm]

I did 3 things and shot some more this morning. All cases ejected and all but one fed properly. I tried the first load as a single in the mag and it even locked the bolt back. The rims look good, no metal missing where the extractor jumped. One thing odd that I noticed was the primers were not as flat with the same load. It was maybe 5 degrees cooler, not enough to make that much differance.
I oiled the BCG.
I polished the chamber with JB.
The barrel is a nonstandard profile and very thin. The gas block is modified to fit the barrel. I played around with limiting the gas flow through the gas block. I blocked almost half the port.
I think the main problem is the required port size must be tied to barrel diameter. In fluid flow it is not only the diameter of the oriface but also the length. I think the thin barrel really needed a much smaller port. I am going to go adjustable in some form and tweak the gas flow. I think my results this morning show that I may have limited the gas flow a little too much. Maybe the first one locked back because of the oil. Maybe I am running on the edge of functioning and the one failure to feed completely was caused by not enough gas flow. It almost fed the bolt just didn't close completely.

Thanks for all the help. I will be doing some more testing.
Chip

[leo6223]

Sounds to me like it might be trying to unlock too early when the pressure is still too high.

That can be a tough fix

[txjm]

I did 3 things and shot some more this morning. All cases ejected and all but one fed properly. I tried the first load as a single in the mag and it even locked the bolt back. The rims look good, no metal missing where the extractor jumped. One thing odd that I noticed was the primers were not as flat with the same load. It was maybe 5 degrees cooler, not enough to make that much differance.
I oiled the BCG.
I polished the chamber with JB.
The barrel is a nonstandard profile and very thin. The gas block is modified to fit the barrel. I played around with limiting the gas flow through the gas block. I blocked almost half the port.

Thanks for all the help. I will be doing some more testing.
Chip

I modified my gas block to be adjustable. I started with lower end loads from above and adjusted until the rifle functioned. Everything seems to be happy now. 85G SGK don't seem to shoot as well as 80G Rem CL. H4895 seems to shoot better than 335. The 80G @ 27K + in the 18" barrel seems to be about it.

Thanks
Chip