The Barnes TAC-TX bullet is a special purpose expanding all-copper bullet that is optimized around AR platforms. AR's feature shorter carbine length barrels which reduce the muzzle velocity when compared to a standard barrel length. To achieve the same terminal performance that Barnes fans are used to, Barnes added a larger tip to allow more fluid to enter the nose and modified the bullet cavity to maximize expansion at lower velocities. These bullets track straighter through barriers and have better weight retention than lead-core bullets.