Our ⅜” AR500 steel targets are ideal for magnum pistol practice from 12 yards, shotgun slugs and pellets from 50 yards, and centerfire rifles with a muzzle velocity less than 2800 FPS if used at least 100 yards from the target. Centerfire rifles with a muzzle velocity greater than 2800 FPS, including magnum loads, may be used if the target is at least 250 yards from the firing line. The ⅜” AR500 line is the most commonly used targets sold by MOA, due to the versatility and affordability of the targets. 5.56x45/.223 is commonly used on these targets. That's fine, just expect pitting with velocities over 2,800 fps.