Used one to sight in my rifle, a buddy was selling his Vortex decided to us instead. Been sitting in my closet ever since collecting dust.
Response scopes are caliber-specific for .223 Rem./5.56 NATO and .308 Win./7.62 NATO. That means the reticles are designed to match bullet drop for a 55-grain .223 Rem. load or a 168-grain .308 Win. load.