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Help me figure this out. Bulged case head.

H

happyfast79

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Minuteman
    • Mar 27, 2013
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    I just swapped out a factory 20 inch rifle gas psa 6.5 Creedmoor barrel for a 22 inch +2 gas barrel. This was the first firing on star line brass, had some strange rings around the base of the case on lighter loads, then some primers were leaking gas around them on a few pieces of the next few loads.

    The hottest load I checked had a.010 bulge around the back of the case ( belted
    magnum ) and one of those lost a primer and it jammed it's self in the bolt cam pin bore and locked the gun up.. needless to say I stopped there.

    Shot some factory 123 grain federal stuff and brass looked fine, shot some of these same loads with the same brass out of the factory barrel and they looked fine. I did not run a set of headspace gages through this rifle after the barrel change. What are you guys thoughts? Thanks in advance.

    Loads were 39-43 grains of rl17 with 143 eldx set at 2.825 coal. Win primers
     

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    happyfast79 said:
    I just swapped out a factory 20 inch rifle gas psa 6.5 Creedmoor barrel for a 22 inch +2 gas Odin works tactical match barrel. This was the first firing on star line brass, had some strange rings around the base of the case on lighter loads, then some primers were leaking gas around them on a few pieces of the next few loads.

    The hottest load I checked had a.010 bulge around the back of the case ( belted
    magnum ) and one of those lost a primer and it jammed it's self in the bolt cam pin bore and locked the gun up.. needless to say I stopped there.

    Shot some factory 123 grain federal stuff and brass looked fine, shot some of these same loads with the same brass out of the factory barrel and they looked fine. I did not run a set of headspace gages through this rifle after the barrel change. What are you guys thoughts? Thanks in advance.

    Loads were 39-43 grains of rl17 with 143 eldx set at 2.825 coal. Win primers
    Click to expand...
    Well, that looks like insipient case head separation. Combined with ‘primer leakage’ and a “lost primer” I’d say you have found and exceeded max pressure. Have you measured how much growth in case length from unfired to fired? That might give you some info on the chamber. But again, blown and lost primers are generally good sighs of over pressure.
     
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    hlee said:
    Well, that looks like insipient case head separation. Combined with ‘primer leakage’ and a “lost primer” I’d say you have found and exceeded max pressure. Have you measured how much growth in case length from unfired to fired? That might give you some info on the chamber. But again, blown and lost primers are generally good sighs of over pressure.
    Click to expand...
    The case head separation that I have seen. in the past doesnt expand out like these did. That ring is .010 bigger than the rest of the case. Isn't that part of the case supposed to be in the chamber? I'll do some more measurements and get back with you on the length.
     
    happyfast79 said:
    The case head separation that I have seen. in the past doesnt expand out like these did. That ring is .010 bigger than the rest of the case. Isn't that part of the case supposed to be in the chamber? I'll do some more measurements and get back with you on the length.
    Click to expand...
    Check the chamber specs in this thread…

    www.snipershide.com

    6.5 Creed & 6.5 PRC

    Can factory 6.5 Creed be fired in a 6.5 PRC to obtain brass? What about headspace? Will the brass be usable or is this too big a stretch?
    www.snipershide.com www.snipershide.com
     
    So my case diameters are in spec except for that ring and it is .474-.481 on the hotter loads but .470 right in front of that ring. Case length on virgin brass is 1.909 and most of the fired stuff shrunk to 1.899 , with a few odd ball ones being 1.894 and 1.918
     
    happyfast79 said:
    So my case diameters are in spec except for that ring and it is .474-.481 on the hotter loads but .470 right in front of that ring. Case length on virgin brass is 1.909 and most of the fired stuff shrunk to 1.899 , with a few odd ball ones being 1.894 and 1.918
    Click to expand...
    The overall length of the fired case is less important than the shoulder measurement- from the back of the case to the 0.400" measurement on the shoulder. The OAL may shrink as brass is "used" to blow out the shoulder upon firing.
     
    happyfast79 said:
    This was the first firing on star line brass, had some strange rings around the base of the case on lighter loads, then some primers were leaking gas around them on a few pieces of the next few loads . . . The hottest load I checked had a.010 bulge around the back of the case . . .

    Shot some factory 123 grain federal stuff and brass looked fine, shot some of these same loads with the same brass out of the factory barrel and they looked fine.
    Click to expand...

    Those are what is known as "clues."

    Your loads are over-pressure in that barrel. The "ring" that you're seeing is the brass flowing into the recess of the barrel extension.

    pic_04-2076597.jpg



    pic_01-2076594.jpg



    pic_02-2076595.jpg





    pic_03-2076596.jpg




    ...
     
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    hlee said:
    The overall length of the fired case is less important than the shoulder measurement- from the back of the case to the 0.400" measurement on the shoulder. The OAL may shrink as brass is "used" to blow out the shoulder upon firing.
    Click to expand...
    Thats
    Molon said:
    Those are what is known as "clues."

    Your loads are over-pressure in that barrel. The "ring" that you're seeing is the brass flowing into recess of the barrel extension.

    pic_04-2076597.jpg



    pic_01-2076594.jpg



    pic_02-2076595.jpg





    pic_03-2076596.jpg




    ...
    Click to expand...
    Thanks for the pictures, I wasn't sure if there was that much unsupported case in a AR. So maybe I need to abandon reloader 17 in this cartridge. I thought I started pretty low on the charge and even on the first loads u could see a line in that spot. And barrel didn't seem to shoot well with any of those loads. Any chance on my brass being soft?
     
    happyfast79 said:
    Thats

    Thanks for the pictures, I wasn't sure if there was that much unsupported case in a AR. So maybe I need to abandon reloader 17 in this cartridge. I thought I started pretty low on the charge and even on the first loads u could see a line in that spot. And barrel didn't seem to shoot well with any of those loads. Any chance on my brass being soft?
    Click to expand...

    Doubtful. I'd say there's just a really good chance that you are way over pressure , like @Molon just told you.
     
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    Aftermath said:
    HAHAHAHAHAHAHAHAHA!!!!!
    :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO: :ROFLMAO:
    OP: I have shit happening and I don't have a fucking clue what is going on, please help.
    OP: You guys don't know shit.
    Click to expand...
    Lol not quite, just making sure I've got my bases covered. I've never used starline rifle brass before so I just wanted to make sure. I'm used to seeing pressure signs on the back of the case at the ejector, so this one threw me for a loop.
     
    From my observance over the years, anytime Molon gets involved you're fixing to learn some shit. Listen to Molon. That is all.
     
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    mtrmn said:
    From my observance over the years, anytime Molon gets involved you're fixing to learn some shit. Listen to Molon. That is all.
    Click to expand...
    Good to know. Thanks for the heads up
    Molon said:
    Those are what is known as "clues."

    Your loads are over-pressure in that barrel. The "ring" that you're seeing is the brass flowing into the recess of the barrel extension.


    pic_04-2076597.jpg



    pic_01-2076594.jpg



    pic_02-2076595.jpg





    pic_03-2076596.jpg



    I'll back way down and see how it does. Thanks for the info and pictures
    Click to expand...
     
    TheOfficeT-Rex said:
    If it's not pissing hot, it's not Hide Load Data...




    Hornady book lists 41.3 as max with that combo. FYSA.
    Click to expand...
    This is the load data I was going off. I looked at my loads and I started at 39 and top load was 42 grains of rl17. Happen to have a picture of the page in the newer manual?
     

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    I'm lazy, have a google image. This is tenth book, there's a new one out.
     
    mtrmn said:
    From my observance over the years, anytime Molon gets involved you're fixing to learn some shit. Listen to Molon. That is all.
    Click to expand...
    That's a fact. Molon not only has the experience with AR's in particular but he also had the equipment to measure about anything and has probably already tested it with documentation.
     
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    happyfast79 said:
    Thanks for checking. Any of you guys using Rl17 in a 6.5 gas gun with good results? I'm gonna try to grab some 6.5 staball and try it too
    Click to expand...
    you should get a current book, first. JMHO.

    but admittedly, I'll be the first to say, I don't know shet.
     
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    0DAE6D8C-7185-40AB-8755-2135EFACAC45.jpeg

    ^

    You are literally blowing out primers and bulging the case...
    808A0BFC-C43E-46ED-8354-98FA8BCC03DF.jpeg


    There is more information in those manuals than just charge weights. You are lucky that budge did not blow out and ruin your day.

    You were literally right on the edge of blowing shit up... and seem completely aloof of it.

    Edit- like seating depth. Which you have past the recommended coal.
    image.jpg

    Or trim lenght
    image.jpg


    Who knows what you are doing to cause that dangerously high pressure.
     
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    GreenGO Juan said:
    View attachment 8037111
    ^

    You are literally blowing out primers and bulging the case... View attachment 8037117

    There is more information in those manuals than just charge weights. You are lucky that budge did not blow out and ruin your day.

    You were literally right on the edge of blowing shit up... and seem completely aloof of it.

    Edit- like seating depth. Which you have past the recommended coal. View attachment 8037126
    Or trim lenght
    View attachment 8037127

    Who knows what you are doing to cause that dangerously high pressure.
    Click to expand...
    So that bullet hits the lands at 2.915 , wouldn't increasing coal lower pressure? If not please explain
     
    Increasing OAL isn't going to save you from dropping too much powder in the case. Go back to book starting loads and start over.
     
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    TheOfficeT-Rex said:
    Increasing OAL isn't going to save you from dropping too much powder in the case. Go back to book starting loads and start over.
    Click to expand...
    That's the plan. Thanks. I was just trying to figure out his comment about me having the bullet seated out further than the book says Contributing to higher pressure.
     
    happyfast79 said:
    That's the plan. Thanks. I was just trying to figure out his comment about me having the bullet seated out further than the book says Contributing to higher pressure.
    Click to expand...

    He's telling you to RTFM and re-verify all your steps.
     
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    happyfast79 said:
    So that bullet hits the lands at 2.915 , wouldn't increasing coal lower pressure? If not please explain
    Click to expand...
    Did you read and comprehend that section of manual? How seating depth affects pressure?

    Closer to the lands.
    A) straight Fucks
    B) raises pressure
    C) lowers pressure
    D) she loves the D
    E)depends
    Example below.

    ECC05911-3C8A-45A5-A5FB-1D17A5B79A1E.jpeg



    EBFCE71E-A04B-445A-86BE-58DF8146EE17.jpeg
     
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    GreenGO Juan said:
    Did you read and comprehend that section of manual? How seating depth affects pressure?

    Closer to the lands.
    A) straight Fucks
    B) raises pressure
    C) lowers pressure
    D) she loves the D
    E)depends
    Example below.

    View attachment 8037198


    View attachment 8037199
    Click to expand...
    So me extending the bullet out of the case .025 and still being .090 off the rifling should decrease chamber pressure.
     
    B y r o n said:
    That load data was for 140 gr bullet and you were using 143 gr.
    Click to expand...
    Yes and have been given the load data in this thread to start again with. 140 gr bullet max was 42gr and the 143 gr max was 41.3 gr.
    GreenGO Juan said:
    You are seeing extreme pressure signs and you think your process is lowering the chamber pressure?

    Good luck!
    Click to expand...
    I'm asking about in theory, there is no doubt that I had over pressure, that horse has already been beat enough. My question on this is if someone with a perfectly safe pressure load (not mine that wasnt) , seats the bullet out of the case .025 ( so case capacity is increased by the bullet taking up less powder space) and that bullet is still .090 from the rifling ( not jammed). In theory would drop chamber pressure? I'm looking to learn here, so give me some meaningful feed back.
     
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    I think that the OP wants to learn. He’s recognized and admitted now that he was over pressure. Here’s what has been discussed so far:

    1. He should step back for a little bit to read his reloading manual’s first chapters. The ones not just listing loads. The ones that give a quick lesson about safe practices and the important basics to follow.

    2. As was hinted at but not detailed; given all things the same, a heavier bullet with a charge used for lighter bullets will create more pressure. Sometimes too much pressure, becoming dangerous.

    3. A blown primer is most often a sign of severe pressure.

    4. When there is metal deformation that is noticeable to the eye, you need to stop immediately and evaluate what you did, before you hurt yourself.

    5. It is hard learning some of these things if you’ve not had a mentor or have any experience in the area. That is why a good bout of reading and measuring things is very, I mean very, important. Until you actually know what you are doing, and then always throughout the process of any hand loading always be measuring dimensions of things.

    6. If you don’t know which things, why, when or how. Do more reading and ask questions until you do.

    There’s more, much more, but I think the point has been made.
     
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