where to find straight shank split mandrel

[Catgunguy]

I need a split mandrel to enlarge a bullet comparitor insert closer to bullet diameter.
The one I have measures .296 and want to open it up to .306.

I have tried the internet but have not found any tool supply stores that sell them.
I plan to use a piece of emery cloth in the split mandrel to open it up.

Any help greatly appreciated.

 

[Texas10]

I made my own using a 1/4 inch bolt, sanded to a slight taper and then split with a cut-off wheel or a hack saw.

I prefer to fold the emery cloth once at a diagonal in the middle so that both sides sand.

 

[jepp2]

Any help greatly appreciated.

I use laps to hone my die necks. Much more controllable than a flap wheel.
https://www.mscdirect.com/browse/tn/Abrasives/Through-Hole-Laps?searchterm=laps&navid=4287920987

 

[ronemus]

You might consider a straight 4-flute reamer in the size you need - they're fairly inexpensive and will give you a round hole which would be a potential problem with an arbor/abrasive.

 

[Catgunguy]

Thank you for your help. I do want it to be a uniform diameter.