COAL: 2.250 Powder: SMP 735 Powder Weight: 22.2GR Test Barrel Length/Twist: 24 1:7 Multi-Patented, Tumble Upon Impact design Superior penetration Non lead, Solid Copper Spun SCS bullet Fort Scott Munitions 5.56 NATO Tumble Upon Impact ammunition is an all-in-one designed cartridge. From hunting, match shooting, to everyday carry self-defense, this 556 ammo offers superior results for every occasion. The TUI bullets are machined from solid copper or brass rods on a CNC lathe. With the quality control that we require every day and the tight tolerances we keep our projectiles, you are able to trust and expect the same results with every pull of the trigger. With the bullets being solid copper or brass, you have no moving parts to rely on. Unlike most ammo, the TUI rounds do the most damage internally instead of first contact with skin. With our patented design, our TUI ammo tumbles end over end when it comes in contact with water-based tissue, creating a more devastating wound channel.