Ring On S&B 60 9x19 9mm Luger Casing

 

9mm Luger S&B 60 9x19 Casing on Right, AD 98 9mm Casing on Left
9mm Luger S&B 60 9x19 Casing on Right
AD 98 9mm Casing on Left 

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Reloading S&B 9MM Luger Casings

I was inspecting my reloads as a part of my quality control program and I came across marks or rings on some cases. I don't know if they are machining marks from the manufacturer or are from deformation, stretching or being reloaded too many times. There is no appreciable difference in the lengths of the cases that I can measure. I don't think they are a concern but I am looking for another opinion. I found 6 casings with these marking, all from the same manufacturer (S&B). Not all S&B's have these. The "deformation" is a circumferential line or ring near the extraction groove. See also Ammunition Reloading Instruction & Reviews.

 

 

Investigating the Ring Marks on a 9mm Luger Brass Case

 
I just checked two boxes of new Blazer Brass and found no traces of this marking on the new ammo.
 
I then grabbed a handful of cleaned brass and examined those.
Out of the 36 that I randomly grabbed:
15 had similar marks (7 were S&B, 8 were four other brands)
21 had no marks
 
I tested each of my dies on an unmarked casing and none caused a similar mark.
 
I then grabbed a couple of handfuls of dirty range ammo and examined those.
Out of 81 random cases:
61 had no marks
15 had similar marks (8 were S&Bs)
5 had similar marks about 1/10th inch higher in location (no S&Bs)
 
On some cases the marks were not evident on all sides of the case. Some marks were more pronounced than others.

I then ran 5 of the dirty unmarked cases through my resizer die. With dirty cases it may be easier to see if the die caused the marks. Some showed a trace of the mark where none had been before. I now believe that this is where the die stops on the case. I analyzed the adjustment on my die and it appears to be adjusted properly.

 

References

Lee carbide dies are contour ground to provide step-less sizing. After sizing a case, except for the burnish, you cannot tell where the sizer stopped. Other brands leave a pronounced step where the die stops. http://www.leeprecision.com/html/catalog/dies-pistol.html

It sounds to me like the "step" to which you refer is the step up in diameter of the cartridge case near the case head and the body of the case (after sizing) that the sizing die leaves. Since the sizing die cannot reach all the way to the rim (because the case holder has to grip the rim somehow) there will be an unavoidable step wherever the sizing die stops.

Right to be concerned, but no danger there
You are right about how it looks, but wrong about the danger. The part below the step is less likely to be brittle and separate than the rest of the cartridge, having never been cold-worked by a die. The part above the step has been worked more, but the mouth is where you will see brittleness make its presence known, as it is worked by the sizing die, then the expander/flarer, then the crimp. So the case mouth is worked three times for every firing and the body only once.

The wall thickness between the once-worked body of the case and the never-worked part below the transition is usually a little bit thicker than the body of the case, too. It may look odd from the outside, but the metal is likely stronger than the rest of the case body further up.
http://www.thefiringline.com/forums/showthread.php?p=3914070

It would appear that is just the "line" that shows how far the case fits into the die -- To check for "head separation" take a paper clip, or similar wire, bend a little right angle on the end, then pass it into the case to the area that appears thin. You will be able to feel any separation ring, if one is forming -- my ha-penny http://www.calguns.net/calgunforum/showthread.php?t=200039

 

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Sent: Monday, November 22, 2010
Subject: Ring On Blazer Brass

I see the same stuff on my Blazer brass. Looking at the brass before resizing shows no bright rings but if I put it through the resizing die I get this line. The line is reduced if I use Oneshot lube but it is always there. I measured the outer diameter before and after resizing and this measurement did not change. When inspecting the inside of the case I see a very fine line at the same distance where this line forms on the outside of the case after resizing.

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