My 6yo woke me up crawling into my bed asking for something to drink. I decided to look at my computer to give him a head start falling asleep before the Big Snoring Bear laid down again... It probably doesn't matter whether you chamfer before or after expanding case neck for the lathe so long as you do chamfer at some point to help initially ease the bullet into the case. For my bulk ammo I just run brass through FL Sizing Die with Expander Ball. However, for my precision reloads I have removed the expander ball and use a neck expander die/mandrel to facilitate additional case prep steps and also exact neck tension for specific rifle. I may start using neck expander die on my progressive press for my bulk ammo.... who knows... 2022 might get crazy at my house.No I chamfer before I expand case necks, that way the expander can smooth out the edge of the chamfer as it enters. At least that's my line of thought
The order of my case prep for precision reloading includes:
(1) anneal cases after every shot;
(2) expand case necks with mandrel (size designated by lathe) for neck turning (if needed);
(3) trim to desired case length (3-way trimmer also chamfers both inside and outside case mouth). ;
(4) expand case necks to final ID for desired neck tension (use dry lube)...
The mandrels for both the neck turning lathe and the neck expander are both tapered and don't need the case mouth chamfered.... unless there is a bur from cutting/forming wildcat cases.