603, I did read all of your post. All I did was counter your 3-shot claims.
For all I know, I'll applaud your 15-shot group you pick as the best.
Regarding expander balls, they're best used as slingshot ammo. Their only place in a full length sizing die is when uniforming new case neck to the same dimensions.
Put the bushing in the die whatever sizes case necks the right diameter on their inside to hold the bullet just right for you.
US Navy Distinguished Marksman Badge 153
Former USA Palma Team Member
NRA High Power Long Range High Master
NRA Smallbore Prone Master