I picked the new Superformance GMX 80gr round (fps) which . The copper bullets penetrate much better than the bullets of yesteryear. Chuck Hawks on Hornady GMX bullets. Unlike the % copper Barnes TSX bullet, Hornady's GMX is made from gilding metal, a 95% copper gr. 7MM GMX". gr. 30 Cal. GMX They're no slouch in the penetration department either, routinely penetrating over 30" in gelatin tests.