Case-Head Separation: Causes and How to Spot Problems
On his Riflemans’ Journal blog, German Salazar wrote an excellent article about cartridge Case-Head Separation. We strongly recommend that you read this article. German examines the causes of this serious problem and he explains the ways you can inspect your brass to minimize the risk of a case-head separation. As cases get fired multiple times and then resized during reloading, the cases can stretch. Typically, there is a point in the lower section of the case where the case-walls thin out. This is your “danger zone” and you need to watch for tell-tale signs of weakening.
The photo below shows a case sectioned so that you can see where the case wall becomes thinner near the web. German scribed a little arrow into the soot inside the case pointing to the thinned area. This case hadn’t split yet, but it most likely would do so after one or two more firings.
One great tip offered by German Salazar involves using a bent paper clip to detect potential case wall problems. Slide the paper clip inside your case to check for thin spots. German explains: “This simple little tool (bent paper clip) will let you check the inside of cases before you reload them. The thin spot will be immediately apparent as you run the clip up the inside of the case. If you’re seeing a shiny line on the outside and the clip is really hitting a thin spot inside, it’s time to retire the case. If you do this every time you reload, on at least 15% of your cases, you’ll develop a good feel for what the thin spot feels like and how it gets worse as the case is reloaded more times. And if you’re loading the night before a match and feel pressured for time — don’t skip this step!”
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All the more reason to keep your cases clean, by tumbling, ultra sound, or whatever. If left dirty and reloaded, as I’ve seen many, you will probably not see the impending head seperation ring as it begins to appear.
If you use a pair of side cutter pliers and nip the paper clip end perpendicular to the length, producing a “chisel point”, it provides a more sensitive feel.
I agree with Steves method, I have taken it one step further by using a hook sharpener for fishing which produces a pencil point, you have to find the right sharpener with the inside bowl for the point, after sharpening you make the 90* bend suitable to your cartridge
Ditto on the chisel point. I clip the point of the paper clip with wire cutters at a 45 degree angle to get the point. One thing I didn’t see mentioned is that this is a more pronounced problem with cartridges that headspace on the rim (22 Hornet) or a belt like a belted magnum. It could also be a sign of to much headspace in certain situtations.
Actually, the bright line that is one of the signs of an incipient separation, is probably more visible on an unpolished case, and the reason for the bent paperclip feeler is that it is unlikely that one could reliably detect thinning of of the case wall, so near to the head, by looking down through the case neck. As to the issues that some associate with belted and rimmed cases, there is a difference between having the correct headspace, at the rim or belt, and whether shoulders are moved back(bumped) excessively during sizing. Proper die setup, using the correct measuring tools should minimize, if not eliminate these problems.
As usual, German’s article is well done, and appreciated. Thank you for bringing it to our attention.
HERMAN,
I bet you could get one more firing on that case that you cut! hehe
Another good reason to keep a “broken case extractor” of the proper caliber in your range bag at all times.
One case head seperation with the broken case stuck in the chamber will spoil you range trip. Use the proper tools to remove it without taking the chance of damaging your chamber with bent picks,range rods, etc.
And like Boyd mentioned, Germans articles are “always” well written and very informative.
Don’t mistake cases that have endured a long ride home from a match, or cases that ride around with a truck gun upside down in an mtm box,…. this will give the appearence of a case head sep. I had a friend toss 50 pcs of hard fought .22 Vais brass for this reason,.. he later realized it was just surface wear from vibration in the box. (he didn’t use the probe trick obviously, just took the advise of a “well versed” guncrank working at the front counter in a local gunshop)
I mean this with no disrespect to German or anyone, but typically (in my opinion) this happens mostly because people are too cheap to throw away brass when they should. Let’s put things in perspective – 50000 psi only an inch or so from your face – what’s you eye worth to you?
You should always err on the side of caution and if you start to suspect or see what looks like that situation developing, you should err on the side of caution and ditch the batch of brass you have been firing.
Frankly with some domestic brass, if you get 5 or so reloads on it with FL re-sizing, you have gotten you money’s worth out of the brass, and you may be getting close to living on borrowed time with it by going much further (depending on how much your set up works the brass on re-sizing).
My advice – don’t be stupid smart – understand the risks involved and err on the side of being conservative (i.e. pitch the brass sooner rather than later).
Robert Whitley
I am seeing this more and more on cases where the headspace is excessive within the chamber. It is not unusual to see excessive chamber dpeth coming from ‘smiths now days. I would urge everyone to get a set of go/no go gauges for you rifles. You will be shocked!
I got nocked out of an F-Class nationals because of a case head seperation. I was hydrolic formed virgin brass. I no longer hyrolic form cases. It has been my experience that propperly set dies, good brass care, moderate loads will allow for many reloads. I have loaded my 6BRX brass 1 fireforming and 15-16 reloads before I discard. Three boxes of 100 Lapua brass
and I replace both the brass and the barrel at 3000-3500 rounds.
I keep an eye on the brass and discard questionable pieces.
Nat Lambeth
I’ve known for a while that the chamber in my Mod70 300 WinMag is ‘generous’ and even with neck-sizing only will only get 5~6 reloads before the case head separates. Darn thing shoots well (for a hunting rifle) so I just buy new brass.
One advantage to sharper shoulder angles is that they do a better job of keeping cases from being forced forward in the chamber during firing. In the past, I found that for my .220 Swift that if i set the FL die to give the same shoulder to head measurement as a fired case, that with the diameter of the body slightly reduced, that no bump was required to get a satisfactory bolt close feel, and that if I bumped the shoulder even a little (measured), that a bright line would appear on the next firing. If you have a smooth chamber, and a small shoulder angle, the case will be driven forward quite a bit during firing. In this situation, giving the case more of a run at the chamber shoulder by bumping, makes the situation worse, and may not be necessary to achieve a satisfactory bolt close feel.
I look at the inside of the case with a small, but bright, flashlight. You can see the ‘rings’ or ‘valleys’ start to form and know that the case is starting to lose life. You can check how deep they are with the paper clip tool, but you’ll see the ‘valleys’ get darker(from the shadow being cast over it) and start to cull the cases as needed. The trick is to look at am angle, tilting the case mouth down a little as you spin the case in your fingers. Works for me.
Several years ago I reformed some .223 military into .222 Rem. I was shooting cast bullets at low chamber pressure. With only two loadings like that, I was prepping them to load. About 18% of them showed case head separation. Anyone have aa clue why they started to fail?