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Old September 5, 1999, 10:40 PM   #1
Big Bunny
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Join Date: August 9, 1999
Location: New South Wales - Australia
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I have a puzzle. Anyone - please - give me a clue on this problem? Advice is welcome from all quarters...
Well, I fired x50, two packets(lost 3 in grass)of new 6.5x55mm factory (mil. surplus manf.1976 @ 2,500FPS) 140gn lead core/steel jacket,nickle coated FMJBT at the recent SSAA 30rd(+sighters over 100-200-300m ranges) National Military Postal Match, all with the same Swedish M38 carbine bolt-action mauser-designed M96 rifle, but at different firing rates.
No problems were experienced and it was a good day at the range.
But at home, on reloading the batch, 29 rounds were AOK, 12 were a bit sticky, but 6 failed to chamber completely, due to lack of clearance around 10mm above the rim, as shown by a ring of bright brass there.
How cound have this happened ?
Poor quality Norma brass...unlikely surely.
Heating-up in rapid fire sections ?
Distortion on decapping the berdan primers? But surely in the wrong place for the RCBS tool?
Rim distortion by the claw perhaps?

I was the only 6.5x55mm shooter in the match, so substitution of shells from another rifle is precluded.Though this is the usual problem I have in club events.
I have been reloading for 10 years and never had this problem before. Usually if it comes from a rifle (once fired), it goes back.
Now I can FL re-size them all OK - no problem, but WHY did it happen?
I can only think that other rounds were substituted somewhere from another source. I have some friends who do do practical jokes but they wouldn't do this . An ignorant well-wisher perhaps throwing some "extras" into my pail?
Your thoughts please gentlemen.

***Big Bunny***
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Old September 6, 1999, 01:07 PM   #2
Paul B.
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Join Date: March 28, 1999
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Big bunny. Discounting practical jokers and well wishers, (helpful friendlies ???) Several thoughts crossed my mind. If I understand your post correctly, you neck sized your brass? Maybe some of the rounds were a bit hotter than the others.
You did not state if you checked case length. Maybe some of the rounds are a bit longer?
It could also be that some of the brass might just be a bit softer. I would separate those rounds, shoot them again to see if they have the problem again, in comparison with those that did not over-expand.
Don't know if the answer is there, but I hope it helps.
Paul B.
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Old September 6, 1999, 04:36 PM   #3
Big Bunny
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Yes Paul, you are correct -the brass was neck-sized (only) prior to second firing, but were checked for length and trimmed when neccessary on a mini-lathe. Thankfully, have only 3 to unload with the Quinetics impact hammer in the 9 round trial batch using the Sierras and ADI 2208. Power seems OK for standard mil sights, but may reduce 1/2 grain to 27.5 to allow for summer heat.
Ah, wise words indeed about the brass !
My Club captain, a former tool-maker(ret) came to the same conclusion, despite no prior problems with the NORMA brass in this 200 round batch it is always possible in mass-production to get variables. Also he queried the ambient temperatures the rounds was fired at in relation to cold climate powder sensitivity. Some of Sweden is sub-arctic, I am told.
In OZ we have far higher temperatures than Sweden and additionally with 10 rounds fired in 2 mins for the final "mad mimute" in the SSAA Mil Match, this could have adversely affected pressures, assuming that powders used in all the cases were equal in volume and potency.
We do have problems here with a wide temperature range over pressures, some including myself keep our ammo in "eskys"(portable coolers)for that reason.
Our local ADI powders are apparently advertised as especially formulated for our hot conditions, some are even marketed under the 'Hogden' brand in the US-(Mulwex formerly).
I have even had problems with Winchester SUB-SONICS .22RF (long) going supersonic due to the heat, as they are 1,095 FPS and too near the magic barrier.
This is not apprerciated by this bunny shooter, often in prepared positions after a 1hr wait, as it spooks the buns -having a "crack" instead of a modest bang and a swish overhead...or thump..into one of their siblings!
Anyhow enough of this rambling...thank you Paul for your thoughts and courtesy, your posting was much appreciated.
Best wishes and good shooting, ROB.

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Old September 10, 1999, 09:12 PM   #4
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Might want to check the cases for 'incipient head separation' with a paperclip (bend tiny hook in feeler end). Reloading manuals should have some text on this topic. Potentially dangerous.
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Old September 13, 1999, 12:25 PM   #5
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Uhh, you're decapping Berdan-primed cases? Not just poking a hole in the case with a super-strong decapping pin and replacing with Boxers, are you, I hope.?...

If you're using hydraulic decapping, that can result in case body expansion 10mm ahead of the case head. If so, arrange for some sort of support die, or just plan on full-length resizing them every time.

Hope this is not off-base, but that Berdan reference caught my eye.
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