BoydAllen said:You can have the neck tension that you want with a collet die. You just need the appropriate mandrel, just like you use different bushings for a bushing die. The combination of the collet and body gives you the same sort of complete case sizing as a bushing FL die and if your chamber is factory, and your brass unturned is likely to yield straighter brass....than anyone's bushing FL die. That's what it is all about.
Right. I understand that. But we were talking about controlling the degree of neck sizing by only partially closing the collet (short of the mandrel). It CAN be done, but I don't think it's advisable to try and control tension that way because of repeatability issues. Savageshooter86 was right, I was doing it a little at a time to see where the runout was going wrong.
For example, my fired cases measure .269. After normally Lee collet sizing, they measure .266. By controlling the depth of the collet die in the press, I was able to get .268 (runout was still perfect), .267 (runout was still perfect), a soft .266 (where the neck was just touching the mandrel - runout was still perfect) and finally a hard .266 where the neck was pressed firmly against the mandrel and some runout was induced (with the coax, with the amount of runout depended on how tight the die cap was). I even removed the mandrel and repeated the process for each size down to .266. It would have went smaller without the mandrel, of course, but that was not what I was after.