[How-To] Bore and Turn in a single operation, possible?

dml66 said:
Work holding cartridge brass in a lathe chuck has been a challenge for me. The only approach I've found that will spin a neck with close to zero runout is chucking a straight-shank collet chuck in a 4-jaw. I use a straight-shank ER20, or ER25 collet chuck, itself chucked in a 4-jaw. The trick is mastering the 4-jaw; with practice it becomes 2nd nature. Having said that, some brass hops in the ER collet ready to rock, most of them don't. For the most part, it's time-consuming overall.

This is why once I have a piece trued-up, getting it turned; inside, outside or both, is desirable.

Maybe there are better, faster ways to guide eccentric work into concentricity, I'm just using what works for me.
Click to expand...
Here is how I would approach it. I would use a live center with replaceable tips like this: https://www.shars.com/3mt-medium-duty-live-center-set
and turn a custom tip to fit the cartridge neck like this.
Cartirdge Case Center.JPG
I would purchase a 5C soft steel collet and machine a recess to fit the cartridge rim: https://www.shars.com/5c-emergency-steel-collet.

I would loosely fit the cartridge case in the collet and seat the live center in the neck of the case and then tighten the collet. The tailstock will keep the neck concentric with the spindle axis while the collet will keep the cartridge rim concentric thereby insuring that your cartridge case is concentric with the spindle.
 
Here is a picture from another forum of a very successful shooter turning brass on a lathe.
It won't do the inside of the neck which you really don't want to. But it will work.
I will keep using a conventional neck turning tool powered by my lathe.
Joe
 

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