Need some input

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14 years 10 months ago #2690 by Scaup58
Replied by Scaup58 on topic Re:Need some input
Faceman,
Any denting that happened during feeding or chambering will be erased by the firing event. So, the denting must be happening during extraction and looks an awful lot like barrel extention lug marks. When was the last time the ejector was removed and it's hole cleaned? Also, does the ejector spring stack up before the ejector is flush with the face of the bolt? Are there impressions on the head of the dented cases from the ejector? The only theory I can come up with is that the case is being slapped against the lugs as it's mouth leaves the chamber and the only thing I can think that would do that is the ejector plunger applying excessive force. You didn't say if this is an old or new gun. If new, I would suspect excessive ejector spring length, i.e. an out of tolerance part.

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14 years 10 months ago #2691 by Faceman
Replied by Faceman on topic Re:Need some input
Sorry, the gun is about a year old. I've run about 450 rounds through it so far and cleaned it pretty well between trips to the club, but I don't believe I took the bolt apart for cleaning previous to the last trip. I did run a few rounds through tonight without firing and ejected them slowly. I didn't notice any dents in the cases at all. I guess I'll do a thorough cleaning and head to the range when it warms up a bit and see what happens.
Thanks for all the great info, everyone.

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14 years 10 months ago #2693 by a Guest
Replied by a Guest on topic Re:Need some input
If those cases were the ones in question you have some trash in the chamber. Ether a powder grain or a pc of lint from a patch. I have seen this a bunch. I have it happen regular when using GI patches. Need to follow up with a 308 chamber swab.MSH

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14 years 10 months ago #2694 by Edge
Replied by Edge on topic Re:Need some input
I'm having a hard time with the "hitting the lugs" theory, especially if the dimples are all the way around the shoulder. If there was one dimple, then maybe, but if they are all the way around......no.

I'm leaning more to what mmsshh said, with the chamber being dirty, or that the case is too long.

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14 years 10 months ago #2695 by Edge
Replied by Edge on topic Re:Need some input
Faceman,

Did you clean those cases before you took the photo of them?

I'm just curious as to why there are no signs of being fired, like burnt powder residue.

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14 years 10 months ago #2697 by Scaup58
Replied by Scaup58 on topic Re:Need some input
Well, I agree, my hitting the lugs theory is a long shot. From his picture, it looked like 2 dents which would be from the two lugs opposite the ejector in my theory. No it wouldn't explain the dents all the way around. I thought about MSH's idea, but couldn't reconcile that with it happening on only some rounds. Case length was my first thought too, but he said he trimmed to 2.000". If he's had the rifle a year and this is just now happening, then that shoots the ejector spring too long theory in the ass and in 450 rounds I doubt that enough dirt would have accumulated to hinder ejector plunger movement. I'm not even sure that the geometry is such that the shoulders can contact the lugs once the case mouth is clear of the chamber. On my cases, I see two very small impact marks followed by light scratches cut by the lug edges on the neck as it slides by on the way out, but nothing on the shoulder. So I guess in summary, I don't know! It looks just like a case re-sized with too much lube. If it's crud in the chamber, it must be pretty persistent stuff, but that probably is the most logical explanation.

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14 years 10 months ago #2698 by Scaup58
Replied by Scaup58 on topic Re:Need some input
Well, I agree, my hitting the lugs theory is a long shot. From his picture, it looked like 2 dents which would be from the two lugs opposite the ejector in my theory. No it wouldn't explain the dents all the way around. I thought about MSH's idea, but couldn't reconcile that with it happening on only some rounds. Case length was my first thought too, but he said he trimmed to 2.000". If he's had the rifle a year and this is just now happening, then that shoots the ejector spring too long theory in the ass and in 450 rounds I doubt that enough dirt would have accumulated to hinder ejector plunger movement. I'm not even sure that the geometry is such that the shoulders can contact the lugs once the case mouth is clear of the chamber. On my cases, I see two very small impact marks followed by light scratches cut by the lug edges on the neck as it slides by on the way out, but nothing on the shoulder. So I guess in summary, I don't know! It looks just like a case re-sized with too much lube. If it's crud in the chamber, it must be pretty persistent stuff, but that probably is the most logical explanation.

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14 years 10 months ago #2699 by Faceman
Replied by Faceman on topic Re:Need some input
yes the cases were cleaned prior to the picure, and deprimed, I wanted a good look at them. The actual case lenth is 2.014-2.015. I measured some empty cases. I ran several rounds through several times and no dimples. I did get a lot of crud out of the chamber when i cleaned i las time. I guess I'm gonna have to get a chamber brush instead of a tooth brush, lol. I didn't notice in what order they started to dimple last time I went to the range. It could have happened halfway through when the started to dimple.
Well the rifle is clean and the ejector is working flawlessly so I'll give it a try next time I go.
The cases are ok though, correct?
Thanks.

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14 years 10 months ago #2700 by a Guest
Replied by a Guest on topic Re:Need some input
One of the other things that could happen is that the load is caused increased pressure that is throwing the brass out with such speed that the shell deflecter is doing this. I have seen this and the only way to fix it is to put an adjustable gas manifold on. The gun could be out of time and usually the ream of the case will show a minor bend where the extractor makes contact. This is caused by extracting before the pressure drops on the case. Extraction pressure should be 19500psi and not above that. This allowes the case to relax enough to be yanked out. The powder that is used could also cause pressure spikes that intermit with rounds fired and this is hard to catch when shooting. There has allways been a problem getting people to understand how that works. The SR25 is the worst for this with the plastic buffer that is used. This problem will cause the rifle to selfdistruct with some time and rounds through it. On some of the benchrest rifles they vaper blast 1/3 of the chamber to take pressure off the bolt. That process lets the case to grip the chamber at full pressure then relax.MSH

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14 years 10 months ago #2702 by Edge
Replied by Edge on topic Re:Need some input
Sounds like a dirty chamber is the culprit. Let us know what happens when you fire the next batch.

I would say that your cases are ok, unless you see any splitting or cracking. I've had many cases split and crack from the neck down into the main body. What you don't want is the base of the case to come apart.

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