Maxim Defense Industries Tumble Upon Impact 5.56 NATO 70 Grain Solid Copper Spun 25 Round Box. 56 NATO 70 Grain TUI Ammunition is a match-grade lead-free rifle round engineered for shooters who demand precision penetration and decisive terminal performance. Built around a Solid Copper Spun (SCS) projectile and their Tumble Upon Impact (TUI) technology this ammunition is designed to penetrate deeply and deliver rapid energy transfer upon impact while maintaining excellent accuracy and velocity. Specifications for Maxim Defense Industries Tumble Upon Impact 5.56 NATO 70 Grain Solid Copper Spun 25 Round Box: Manufacturer: Maxim Defense Industries Caliber: 5.56x45mm NATO Number of Rounds: 25 Bullet Weight: 70 grain Additional Features: Copper Features of Maxim Defense Industries Tumble Upon Impact 5.56 NATO 70 Grain Solid Copper Spun 25 Round Box: 5.56 NATO Package Contents: Maxim Defense Industries Tumble Upon Impact 5.56 NATO 70 Grain Solid Copper Spun 25 Round Box