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  #1  
Old 02-13-2010, 5:43 PM
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Nessal Nessal is offline
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Default Overpressure? Pictures inside.

I went to tumble a bunch of brass today and I do my routine checking before I throw it into the tumbler. Of 150 brass casings, there was two that looked to have pressure issues. There is a groove and bump on the headstamp and what looked to be case head seperation. You can feel the groove where the line appears on the case body. This was all shot out of an AR15. What do you guys think?

WARNING VERY BIG PICTURES!

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  #2  
Old 02-13-2010, 5:48 PM
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how are you sizing these?? FL?? Small Base??
i see the ejector marks, but i believe that's common on ARs (?)... correct me if i'm wrong...
how are the primer pockets? can you slip a fresh one in the pocket with ease- does it fall out with little effort?
was there signs of gas leaking around the primer before you deprimed the cases??
have you measured the around the case web for expansion???

Last edited by swerv512; 02-13-2010 at 5:51 PM..
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Old 02-13-2010, 6:14 PM
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have you tried the bent paperclip to see if you can feel a weak spot in the ring? your pic of the end view looks like its bulging slightly. I agree with swerv512 and would measure it for expansion. Just my .02
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Old 02-13-2010, 8:08 PM
J-cat J-cat is offline
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Ejector marks where brass flows into the hole are not common with AR's.
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Old 02-13-2010, 8:12 PM
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what lens are you using? those are nice macro shots
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Old 02-13-2010, 8:16 PM
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I never seen anything like it.
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Old 02-13-2010, 9:30 PM
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Quote:
Originally Posted by J-cat View Post
Ejector marks where brass flows into the hole are not common with AR's.
thanks for the correction. i have seen cases (M700) where the ejector marks were made by a sharp-edged ejectors that once polished, no longer made the marks. i've seen this twice. however, seeing other signs along with the ejector marks could be cause for concern...
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Old 02-13-2010, 10:12 PM
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Them extractor marks lead me to think that you do have some pressure issues. I would cut one of those cases lengthwise to make sure there is no case head separation. What are the specs on the reloads? (Powder charge, bullet, primer and # of times the cases have been reloaded) Also, have you checked your rifle for proper headspace?
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Old 02-13-2010, 10:37 PM
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WOW! Yeah there should not be that much flow in the brass. What are the load details? Powder, amount, primer, bullet type and weight?
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Old 02-13-2010, 10:57 PM
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What do I think?

I think it's a "praise Jesus" miracle your rifle isn't scattered all over the range.

Based ONLY on the appearance of the brass, you are WAY over SAAMI pressure limits.
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Old 02-14-2010, 12:27 AM
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Quote:
Originally Posted by EOD3 View Post
What do I think?

I think it's a "praise Jesus" miracle your rifle isn't scattered all over the range.

Based ONLY on the appearance of the brass, you are WAY over SAAMI pressure limits.
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Old 02-14-2010, 1:19 AM
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Quote:
Originally Posted by swerv512 View Post
how are you sizing these?? FL?? Small Base??
i see the ejector marks, but i believe that's common on ARs (?)... correct me if i'm wrong...
how are the primer pockets? can you slip a fresh one in the pocket with ease- does it fall out with little effort?
was there signs of gas leaking around the primer before you deprimed the cases??
have you measured the around the case web for expansion???

These are full sized. The ejector marks aren't normal I believe. The primer pockets are fine. I primed one of them for the hell and of it and it went in and stayed in. No signs of gas leaking. I haven't measured the case web yet but will do that tomorrow probably.
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Old 02-14-2010, 1:20 AM
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Quote:
Originally Posted by five.five-six View Post
what lens are you using? those are nice macro shots



Just a normal point and shoot Canon SD1000. It's a pretty old camera but works great still!
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Old 02-14-2010, 1:25 AM
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Quote:
Originally Posted by Linus View Post
Them extractor marks lead me to think that you do have some pressure issues. I would cut one of those cases lengthwise to make sure there is no case head separation. What are the specs on the reloads? (Powder charge, bullet, primer and # of times the cases have been reloaded) Also, have you checked your rifle for proper headspace?

I usually shoot a bunch of handle loads in varies grains of bullet. Then check them to make sure that they are ok before they go into the tumbler. So the loads can be either a 75gr load that I've been working on or a 62gr load. These should be twice-third fired brass. The specs of each are....

75gr HPBT
22grn Varget
CCI #41 Primer
medium crimp
Case Length 1.75"
OAL 2.250


62gr FMJ
23grn Varget
CCI #41 Primer
Medium Crimp
Case Length 1.75"
OAL 2.250


It's really weird because none of the other cases have this happen and I was using VERY conservative charges. I loaded thousands of rounds and never had this happen ever. What other possible reasons? Possible that the bullet got pushed in when hitting the feed ramp causing excess pressure? I'm stumped here.

Last edited by Nessal; 02-14-2010 at 1:28 AM..
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Old 02-14-2010, 4:11 AM
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Yes. Over pressure. Be happy you didn't lose something along the way. Back off to minimum loads and start over.
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Old 02-14-2010, 5:42 AM
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Maybe it's me: I see brass which somehow was sized too much, so the brass expanded towards a head-separation and slammed into the ejector pin causing that mark. I'd expect that overpressure would have wiped out much of the lettering on the head. Where did you get that brass? What's your variance on the powder grains?
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Old 02-14-2010, 9:04 AM
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Quote:
Originally Posted by Nessal View Post
I usually shoot a bunch of handle loads in varies grains of bullet. Then check them to make sure that they are ok before they go into the tumbler. So the loads can be either a 75gr load that I've been working on or a 62gr load. These should be twice-third fired brass. The specs of each are....

75gr HPBT
22grn Varget
CCI #41 Primer
medium crimp
Case Length 1.75"
OAL 2.250


62gr FMJ
23grn Varget
CCI #41 Primer
Medium Crimp
Case Length 1.75"
OAL 2.250


It's really weird because none of the other cases have this happen and I was using VERY conservative charges. I loaded thousands of rounds and never had this happen ever. What other possible reasons? Possible that the bullet got pushed in when hitting the feed ramp causing excess pressure? I'm stumped here.
Possibly.

If you have a micrometer, you should mike the case heads to see how much they really expanded. Are the primer pockets loose?
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Old 02-14-2010, 11:34 AM
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OK, please note that I'm in the middle of a move and don't have a clue which box has my reloading books...

I think? the 75 grain bullet may be seated too deep. Check the OAL and give them the "thumb" test.
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Old 02-14-2010, 4:09 PM
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Quote:
Originally Posted by sonnyt650 View Post
Maybe it's me: I see brass which somehow was sized too much, so the brass expanded towards a head-separation and slammed into the ejector pin causing that mark. I'd expect that overpressure would have wiped out much of the lettering on the head. Where did you get that brass? What's your variance on the powder grains?


The brass was new ammo that i shot myself. There are no real variance between the charges. I measure on a digital scale and reference with a beam scale every 5 charges.
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Old 02-14-2010, 4:13 PM
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Quote:
Originally Posted by EOD3 View Post
OK, please note that I'm in the middle of a move and don't have a clue which box has my reloading books...

I think? the 75 grain bullet may be seated too deep. Check the OAL and give them the "thumb" test.
I'll check them again. I think my LEE manual stated 2.260" possibly. I will have to check if i made that mistake. I have another 80 rounds that i will pull because of this to be safe. But none of these were compress loads so i didnt figure if the bullet was in one thousand of an inch, it would overpressure by that much. .
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Old 02-14-2010, 9:27 PM
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Those cases look like they were loaded to about 85,000psi.

That's some serious plastic deformation there.
You are lucky they did not yield completely.
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Old 02-14-2010, 10:57 PM
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Quote:
Originally Posted by Nessal View Post
I'll check them again. I think my LEE manual stated 2.260" possibly. I will have to check if i made that mistake. I have another 80 rounds that i will pull because of this to be safe. But none of these were compress loads so i didnt figure if the bullet was in one thousand of an inch, it would overpressure by that much. .
IIRC, the SAAMI maximum OAL for the .223 is 2.260. A small reduction in case volume can go a long way but I doubt that would cause the kind of pressure spike you're seeing. My main concern would be the case mouth extending onto the ogive which would just about guarantee the bullet would slip further/completely into the case when it hits the feed ramp.
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