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.
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.