8mm Nambu Cartridge Conversion

[sheepherder]

There are several sites with mention of using 38 Special cases to make 8mm Nambu cartridges. RCBS even makes a conversion die set. I decided to make some of my own 8mm cases from 38 Special.

Using once fired cases, I de-primed them using my 44 Special sizing die with the 22-250 decapping pin. The rim needs to be turned down to ~.415", so I mount a case on a 9mm drill bit and clamp it in my lathe chuck. Using a parting tool I turn the 38 Special case rim down to ~.415"

[pic 12]

Next step is to cut the extractor groove, again using a parting tool, but smaller. I cut it to .357" dia.

[pic 13]

After grooving, I cut a chamfer on the forward edge of the extractor groove, using the wider parting tool again.

[pic 14]

After the chamfer is cut and before releasing the case from the chuck, I run a file against the outer edge of the rim to facilitate the extractor engaging the case when feeding.

Cases are now ready for forming.