223 Remington / 5.56mm NATO Case head Sizing Die

.223 Remington / 5.56mm NATO Case head Sizing Die

There are some known issues when reloading the .223 Remington / 5.56mm NATO for AR-15’s that will cause stuck cases in the chamber preventing the rifle from going into battery and firing and also the round can be so wedged in the chamber that it cannot be easily extracted.

The problem mostly exist with reloaded military brass but can also happen with commercial brass. If you have tried small base dies and your brass or loaded rounds will not pass a case gauge test or you are still having trouble with stuck rounds in your AR-15 then you most likely have an oversize case head and or case rim. The maximum case head diameter is .376", the maximum case rim diameter is .378".

Most cases that have an oversize head are military brass that has had the primer crimp removed with a primer pocket swaging tool. These primer pocket swaging tools can have the side effect of slightly expanding the head and rim. But we have seen over size case heads in some commercial brass as well.

Full length resizing dies and even small base dies cannot resize the case head. The only practical way to size the case head is to pass the case completely through a .376" die designed for this purpose. We have designed a special die to do this. The die screws in any standard press for 7/8" dies. Then there is a cartridge ram that fits into the shell holder slot in your press that will push the brass completely through the die. No lube is needed. A catching cup mounts on top of the die to catch the brass as it’s processed.

You should first size the brass with a normal full length sizing die or a small bass die then gauge your brass with a .223 Rem case gauge like the one made by Lyman or a similar one. Trim the brass if needed. Any brass that will not pass your case gauge test should be ran thru this case head sizing die and then case gauged again. The case should now pass the gauge test.

Note, normally the case rims will be slightly bigger than the case head where the case head should be .376", the case rims can be up to .378" so the case rims after going thru this die will now all be no larger than .376". This small difference will not make any difference in the operation of the rifle as many case rims will come .376" from the factory any way.

.223 Remington / 5.56mm NATO brass that is properly trimmed to the correct length of 1.76" passes a case gauge test and loaded no longer than the maximum loaded length of 2.26”"can be relied upon to chamber properly in any rifle.

Made by: LG Outdoors

Model Number: LG223CH

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