Interchange GMX bullets with your field-proven Hornady SST bullet loads without any downloading – they are guaranteed to work with standard published reloading data. Monolithic GMX (Gliding Metal eXpanding) bullets expand to 1-1/2 times their orignal diameter on impact, while retaining more than 95% of their original weight for maximum effectiveness. Tests show GMX bullets penetrate more than 30" in gelatin; its famous Gilding Metal jacket reduces pressure and fouling for professional-grade performance.