I have found a US report on HV tests with fin-stabilized projectiles.
All in all very theoretical but the projectile and cartridges are shown.
As I never saw these before I thought I’d post them here for our flechette and APFSDS aficionados.
The one to the left obviously is a 12.7x99, the right one I assume to be a necked down .60 making it a 12.7x114 (let me know if I am wrong).
