Introduced in 2007, the Varmint Grenade has rapidly become one of the most popular varmint bullets around. Based on a design Barnes developed for military applications, the hollow-cavity, flat-base bullet features a copper-tin powdered metal core surrounded by a guilding metal jacket. The bullet remains intact at ultra-high velocities in fast twist barrels, while its highly frangible core fragments violently on impact. Produces instant fragmentation, virtually vaporizing ground squirrels and prairie dogs, even at long range. Varmint Grenades instantly expend their energy, seldom exiting large predators like bobcats and coyotes, leaving valuable pelts virtually undamaged. 1:10 inches or faster twist rate