YIKES! Torn case rims on once-fired S&B .223 brass ~ what's the cause


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nitesite
January 14, 2007, 11:28 PM
A good friend, who attends several tactical training schools every year, brought back a bucket of brass and shared it with me. The academy only allowed factory new ammunition to be used and students were encouraged to take the scrounged brass out with them.

A lot of it was R-P and Federal (yeah, I won't be using the FC stuff), but around 600 cases were S&B. As I was sorting through everything I quickly noticed that about 25%-30% of the S&B cases had varying degrees of torn rims. Here's one of the more extreme examples:

http://i4.photobucket.com/albums/y141/nitesite9/torn-SB-case-rim.jpg

Is this caused by-

a) soft brass
b) a particular rifle with a very dirty chamber experiencing difficult extraction
c) a particular rifle with a damaged or out-of-spec (too long) extractor
d) something else

It appears that the extractor claw was contacting the groove properly (not just on the outermost edge of the rim). If the extractor was too long then it would moving rearward when it contacted the rim, right?

Maybe these came from a rifle that was owned by a guy who wanted to see how long his AR could go without cleaning and by day three it was fighting hard to extract each round?

I really feel that this was a case of one rifle on that range that was experiencing "issues" but that can't dispel my doubt that the whole bunch might be made of really soft brass. So help me, please!

One more question...

Are the primers so tight that de-capping this brass might break the pin on my Lee sizing die?

I am aware of the issues with S&B regarding tight primer pockets. If this is reloadable I will ream the primer pockets after sizing and trimming.

Thanks much for any helpful comments!!! :)

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DaveInFloweryBranchGA
January 15, 2007, 07:54 AM
"As I was sorting through everything I quickly noticed that about 25%-30% of the S&B cases had varying degrees of torn rims. Here's one of the more extreme examples:"

If it was 100% of the S&B, logic would dictate it was a brass issue. But it's not 100% of the S&B brass. Without knowing the total quantity of S&B brass, I can't comment, especially since I wasn't there when everything was scrounged. But logically, it's not the brass.

"Is this caused by-

a) soft brass
b) a particular rifle with a very dirty chamber experiencing difficult extraction
c) a particular rifle with a damaged or out-of-spec (too long) extractor
d) something else"

a) soft brass - I just resized some S&B brass and I didn't get the impression that brand was soft, but I have a very small sample and not in .223. Based on the sampling percentage above, I doubt it's the brass.

b) difficult extraction - this is most likely the culprit, but there are multiple reasons why a gun won't extract properly, including reloads that are loaded too hot, a dirty chamber, a badly cut/roughly cut chamber, a slightly undersized chamber I do notice a distinct ring on the brass in the picture I've not seen with M16's or AR15 rifles I've shot. I'm wondering what sort of pressure signs the primers are giving.

c) It looks like the extractor is doing it's job. It's grabbing hold of the rim and hanging on tightly as the bolt moves to the rear. It obviously has good springs, likely a crane o-ring or other such goodies in it. I'm not suspecting the extractor, if it appears the extractor isn't too long or too short. If it looks like it dropped down over the brass, then mashed the brass as it pulled it out (This isn't an extracor type problem, but a sticky chamber.), then the extractor did it's job as designed, which was to get the brass out regardless of what condition it was in.

D) The something else I've voting for is problems with the rifle's chamber in a single rifle. Why? Because not all of the S&B brass is damaged as you described. Also, no other brass is having the issue. These two combine to make me wonder if it isn't a chamber that was rough and/or filthy to begin with and began to have extraction problems as it becamse more filthy over the extensive amount of rounds fired in a tactical course.

"It appears that the extractor claw was contacting the groove properly (not just on the outermost edge of the rim). If the extractor was too long then it would moving rearward when it contacted the rim, right?"

If it was too long, you'd see marks farther up on the casing, away from the rim the amount of distance the extractor was too long. Not sure if I'm describing this right.

"Maybe these came from a rifle that was owned by a guy who wanted to see how long his AR could go without cleaning and by day three it was fighting hard to extract each round?"

Possibly, but he'd be a damn fool for spending that kinda money on a tactical course, then do something goofy like that. But I've seen fools that'd do such things. I'm suspecting it's a problem with a rough badly machined chamber or as you said, a goofus playing with his gun.

"I really feel that this was a case of one rifle on that range that was experiencing "issues" but that can't dispel my doubt that the whole bunch might be made of really soft brass. So help me, please!"

I tend to agree with you. If it was soft brass, you'd see 100% case rim failure, not 20 or 30%.

"Are the primers so tight that de-capping this brass might break the pin on my Lee sizing die?"

I just resized a good handful of S&B brass in .303 Brit in my Lee dies with zero problems. Just set your clamp so the resizing pin can back out if a primer is too tight and you should be fine.

"I am aware of the issues with S&B regarding tight primer pockets. If this is reloadable I will ream the primer pockets after sizing and trimming."

Based on the way mine felt, the primer pockets had a military style crimp on them. I haven't and didn't do enough checking to confirm this, but it's easy enough to ream or swag the pocket to proper dimensions.

My vote is to reload those puppies unless it's a very small batch. But with rifle cartridge, I'd load them according to brand, to insure I didn't get pressure and velocity variations due to variations in case capacity.

Regards,

Dave

mscott
January 15, 2007, 09:01 AM
I wonder if they might have been shot out of a short-barreled AR15 type weapon? The short guns are known for pulling cases out a tad early during the firing sequence.

The Bushmaster
January 15, 2007, 11:33 AM
Go back and find the culprit rifle. It has a problem that needs to be repaired...:scrutiny:

ilbob
January 15, 2007, 11:36 AM
Seems to me there was a rifle know for doing just this kind of damage to ejected cartridge cases. It might well be normal for that rifle.

Sort of like the painful things HK rifles do to 308 cases.

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