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Posted: 6/20/2010 11:57:10 AM EDT
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I'm noticing a bring ring on some of my .223 brass. I did some searching on the net and believe it is one of two things:
1) A sizing line from my die or 2) Incipient case head separation These cases are mixed headstamps with anywhere from 2-4 loadings on them. Sizing dies used are Lee and RCBS X-Die. Set up was done using a Dillon case gage. I generally do not shoot hot loads. The line is about 3-5 mm up from the extractor groove. I tried the paper clip trick and feel nothing. Will the paper clip trick always work to detect incipient case head separation? Thoughts? |
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Have had two come apart.The ring was there before sizing but I did not know to pay attention to it.
On mine it did not really look like a mark where the die stoped. It looks more like a lighter color ring going around the case and is located closer to where the chamber supported part of the case begins. All the cases were LC cases that were commercially reload once before I reloaded them once or more myself. It is a real pain geting the case out with the new round crammed into it. |
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Many full-length sizing dies do not size far enough down on fired cases (while your shoulder datum headspace is correct as measured in a Wilson or Dillon drop-in case gage). If you measure your cases with a micrometer at the ring you may find your cases are a few thousandths fatter there than virgin unfired brass. It may or may not affect your feeding, chambering, firing, and extration.
You can use your own chamber as a case or cartridge gage. Strip the weapon and drop each resized case or loaded cartridge into the chamber. If it chambers fully and falls freely, no problem. If it requires a gentle to firm push to chamber, and a tap or cleaning rod to get out you need a small base sizing die. Cartridges should freely chamber and fall out under gravity. You will notice fat cases most if your brass is fired in a MILSPEC chamber first, you full-length resize, and then try to shoot the reloads in rifles and carbines with tighter commercial .223 or match chambers. |
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Over the last couple decades loading for AR-15s I have had a few total case head separations and several partial separations. They are for the most part total non events in the AR-15.
A sizing line tends to show up as you noted just above the extractor groove. In my experience with the .223, the bright that appear and indicate an incipent head separation occur a little higher - maybe 1/4 to 1/3 rd of the way up the case. The separation occurs due to excessive stretching of the case either in 1 or 2 shots in a weapon with excessiv e head space or over the course of several loadings in a weapon with normal headspace. In either case, the forward portion of the case adheres to the chamber wall as pressure builds up and it stays there as the head of the case if forced back to the bolt face by that same pressure. In the .223 case, the web is fairly thick so the point where the case does not expand all the way out to the chamber as the pressure begins to bulid is fairly far forward and that point where the case stops being "stuck" to the case wall is where the stretch occurs. In a case with a thinner or faster tapering web, that point will be farther back on the case (closer to the head). In any event, in the AR-15 I have never had a case separation result in gas getting past the head, so the aft portion of the case apparently still does a good job of sealing even when a separation occurs, but it is stilla really good idea to catch those cases before they get reloaded and if you have a rifle that stretches cases in only 1-3 firings, get the headspace checked. |
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Before I bought a case gage, I sized a number of brass too small (bumped the shoulder back too far), and the excessive headspace caused a few case separations for me.
Some of the separations were as close as .5" from the case head, others were over an inch from the head. If you do the paper clip test, when you find an incipient case separation, you'll often see a faint ring around the case in that area. Some I've found have an hairline crack. Others have a bright ring. Others have no external indicator. Take the time to do the paper clip test ( a small, long-shanked allen wrench works well for me) on all cases after a couple loadings. And invest in a case gage early in your reloading career. It will save you time and money in the long run. |
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Quoted:
http://i250.photobucket.com/albums/gg272/dryflash3/PC270335.jpg Top left case is a classic seperation with 223 brass. Look to the right of the split, you can see the crack. Rest of the cases aren't much good either. Bottom 2 are Mil factory rounds. The ring on mine looks similar to the ring on the fifth case from the left. So, basically, if it passes the paper clip test I'm GTG? |
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Quoted:
A sizing line tends to show up as you noted just above the extractor groove. In my experience with the .223, the bright that appear and indicate an incipent head separation occur a little higher - maybe 1/4 to 1/3 rd of the way up the case. What he said The bright line is where your sizing die is stopping and has nothing to do with incipient case head separation which occurs higher up on the case. While I have seen brass start to look different where it would separate, the paper clip test is the only way to test for the internal stretching in 99% of the cases. I have way more of an issue on 308 brass than I do on 223 as 308 gas guns put alot of stress on the brass as it is a more violent extraction and it might have not contracted fully as the bolt is moving rearward. Try to size your brass just enough to funtion properly and you will probably get a lose primer pocket, cracked neck, or lose the brass before the case separates. |
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Dryflash that is some awfully gnarly brass –– it looks like this batch has far more problems than incipient case head separation!
The long cracks look like the cases may have been embrittled somehow (perhaps polished with Brasso with ammonia?). The two bottom rounds are REAL MILSPEC issued ammo, or XM / AE or some other commercial re-labeled stuff? They don't look like they have military annealing. |
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Quoted:
This is a really good idea for learning purposes. Ideally, take cases fired in your rifle 1-5 times and cut each of them lengthwise and you may start to see a pattern emerging. That may then help you decide how many loadings per case is enough.
Well you can always sacrifice a case for your learning. Take a dremel with a cut off wheel and cut a case in half length wise and look at the area in question. I also agree that an incipent head separation line only occurs when the case is real close to going. The more normal pattern is it goes from looking great to a partial separation in one more firing. In that regard a paperclip test is the only reliable means to indicate a problme in the making. On the other hand it is a major PITA and is neither fool proof nor condusive to large ammo reloading processes. for exmapel, the guy firing 500 rounds per week and loading on a Dillon press is not likely to what to paperclip each and every case. In that case, the realistic options are to try to track brass by number of firings and retire them after X number or to shoot them until you see an incipient case separation - which will mean you experience afew partial or full separations. One approach is to mark the brass each time it is reloaded on the head of the case or oin the primer. Multiple marks get confusing on a case head and if one dissapears you are no longer accurately keeping track. Color coding the primer is an option (for exmaple, unmarked =l new or once fired brass, green = 2nd reloading, blue = 3rd reloading , red=4the reloading etc). With that system, you then sort the brass by number of firings determined by the primer color on the fired brass and keep it segregated until re-primed and re-marked with the next color. I have marked case heads before and I used a dot for 1rst reloading of new or once fired brass, extended the dot to a line for the 2nd reloading, made it a T for the 3rd reloading and modified it to a + for the 4th reloading. In the real world, I use a brass catcher on new or once fired brass or shoot in areas where I will recover what I know is my brass. At the average tactical match, I shoot stuff that is nearing end of life and don't bother picking it up, same with field situations where high grass etc, prevents recovery - if I want to recover it I use a brass catcher and if it is tired brass I let it fly. Also, most separation issues I have had occur with carbines and while I love my 11.5" XM177E2 clone, it eats brassa little faster than my SP1, A1, A2 clone and 20" varmint ARs. The major issue is that with higher port pressures, extraction starts earlier with higher pressures in the case, so the bolt starts extracting the case while the forward portion is still stuck to the chamber wall and more stretching is inevitable. If I did not shoot carbines, or kept the carbine and rifle fired cases separate, I could get more life out of my brass as my 20" rifles are much kinder to the brass over several loadings. |
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Case head separations in 5.56 occur more like 8-10mm above the extractor groove. You are probably looking at a sizing ring.
I have zero faith that anyone other than a dentist could reliably feel a groove using a paperclip. If you are worried about it, I agree you should slice open a case. Or just let them fail. I've never seen a case head separation result in anything more serious than a stoppage and a giggle. |
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Quoted:
dryflash that is some awfully gnarly brass –– it looks like this batch has far more problems than incipient case head separation! The long cracks look like the cases may have been embrittled somehow (perhaps polished with Brasso with ammonia?). The two bottom rounds are REAL MILSPEC issued ammo, or XM / AE or some other commercial re-labeled stuff? They don't look like they have military annealing. These are cases that I found while inspecting my cases over the years. Several problems shown. Not all from the same batch. I use FA brass polish, never Brasso here. IIRC Malaysian mil cases on the bottom, no control over their annealing or QC. At least they don't look like this, 
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