So if figured that if all my 20VT brass was made from 221FB brass, why not use a Hornady 221FB modified case to measure oal? So I have gone through all the steps to create my 20VT brass and now I'm ready to determine my bullet seating depth. I also ran the Hornady case through the 20VT fl die and set the neck tension in the modified case so a bullet barely stays in. Now my problem is, when I went to screw the rod from the gauge into the case, it will only screw on a couple of turns and then gets stuck. I checked the threads on both the rod and the cartridge and they both look fine. I have also used this gauge with my 308W numerous times so I know it should work. What I'm wondering is if running the case through the 20VT die had any effect on the head end and distorted the case just a little bit. I wouldn't think so, but I'm not sure what else to look for.