Hi Terry.
I've just changed to custom expander mandrels.
With my bushing dies I've opted to use a smaller bushing so the custom expander mandrel has to work a little more so I get more consistant neck tension.
I use the K&M mandrel holder and custom expander with 1.5 thousandths neck tension.they seat as smΓ²oth as silk and I've no inconsistencies in neck tension from small variations from neck turning where the cutter and pilot got hot.
I was a bit unsure if the K&M mandrel holder and custom expander mandrel would cause runout. To be honest I've not got the kit to check it but I have tried some loads and had some superb results,one of the lots of ammo I tested after using the custom ground mandrels I posted a photo of a 5 shot group I shot using this system thats on the creedmoor pierced primer thread.
Spud will order what you need,there on his website if you want to you can place the order on line.
Look up the K&M kit and you'll find it.
There are alternative custom mandrels and holders, one do one with a rubber bushing thing so the mandrel free float so it so say self centres, I just left a bit of slack in my K&M set up so it will self centre as it has no rubber free floating thingy.
Hope this helps
Atb No I deer