Split Neck Cases

Split Case Necks
A very thin split in the neck or mouth of your cases can be tricky to see with the naked eye during case inspection.  Shining a flashlight through your cases in a darkened room can help you see where any light might be going through.  Once you have found cases with  splits in the neck you may be wondering what caused them, how to prevent splits, and what can be done now with the cases.

Split Neck Causes

Each time a case is loaded, the mouth is sized to accept the next bullet. After the bullet is seated, the neck is crimped to hold the new bullet in place. This constant working of the brass will harden it to the point that it can develop splits in the neck area.

Preventing Split Necks

Unfortunately, split case necks are probably the single most common cause for case loss. Cases can be very expensive to replace, so sometimes as they say and ounce of prevention is worth a pound of cure.

Splits can be reduced by simply not working the brass any more than absolutely necessary. When loading pistol ammunition or straight walled cartridges, don’t bell the case mouth any more than is needed to get the next bullet started, and don’t apply heavy crimps unless the load actually calls for it.

Annealing case necks can help to prolong case life by softening the neck that has become brittle due to resizing and work hardening. Do some research about the annealing process and you just might be able to extend the life of your cases and prevent some case neck splits.

What Now

It is best to scrap any case when it develops a split in the neck or mouth, regardless of the number of firings. Once the case has split, it cannot be repaired. 

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4 Responses to Split Neck Cases

  1. Pingback: Split Neck Cases | Rifleman III Journal

  2. Daryl Davis says:

    I don’t load that many straight wall cases so my regimen is 2 loads and scrap can but with bottleneck cases in larger calibers, when I resize them, I reaize with the expander ball removed and a straight replacement installed. Why? Because when the bullet exits the case when fired it will expand the case neck anyway. Why work the neck again when there is no need to. I also use only bushing dies and set my neck tension according to the end use of the cartridge, in my case medium to long range hunting.

    Why overwork the neck and case premature workhardening (from expanding and contracting the neck 2 times with every reload. No point.

    I typically reload a bottleneck case 4 times and then inspect it and if it’s viable, anneal it. The exception is a belted magnum where normally the belted base will fail before the neck will.

    I always use quality brass such as Lapia or Norma. That gives you a ‘leg up’ so to speak on your end result and case life. You pay a bit more at the outset but in the end, it averages out.

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  3. Richard in NM says:

    Size for your chamber. Do some research on sizing and by all means if you can use an RCBS case mic that tells you how much the cases has lengthened in your chamber at the head space datum point. In semi-autos size .002 below the fired case measurement. Size bolt actions with a FL length sizing die until the bolt closes with no resistance for hunting. For others use a neck sizing die. You would be surprised how many people are over sizing their brass and getting short life span. Especially with belted magnum cases. Belted cases head space off the belt. I size belted magnums by neck sizing only. When chambering the neck sized brass in the action becomes stiff I partially FL size by screwing in the die a little each time until the bolt closes with no resistance. Chambers are different and so are dies. Take some time to understand head space and chamber dimensions and your brass will last a lot longer.

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  4. Keith Carver says:

    Regardless of the cause for the neck cracks; we need to identify those cases that have cracks and remove them from the reloading process. I have found that using a small LED light works the best. The LED light will fit into the case neck (223 or larger) and because it is so bright even the smallest crack will show up; even in a normally lit room. Of course, dimly lit is better. I have found cracks so small that without this method you wouldn’t find them. Harbor Freight has a two light set for $8.99 (Item #95414). I use the larger of the two because I can set it on my workbench and adjust the shaft so that both hands are free to pick-up and rotate the case around for complete inspection.

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