Johnny Buffalo might be chasing critters, so I'll drop in my take on this.
You might try one of Reddings tungsten/carbide floating sizing balls. For the 7X57, it would be Kit No. 49283. The t/c ball floats on the expander and centers itself on the case neck as it exits the die. Literally ALL of my Redding sizing dies are so-equipped.
Having shot prolly a million rounds, I can honestly say I've seen lots of relatively crooked ammunition shoot awfully straight.
Personally, I am a nut on case neck concentricity and sort every case I shoot to .001".
Ammo runout is something I chase only if I am having trouble getting the rifle to shoot and eliminated several other potential causes.
Schit like this can drive a normally-sane man crazy.
Steve
