I've heard there are caliber restrictions - is that true?

Yes, we do keep it restricted to 300 mags or less.  This is primarily because 338 and larger really puts holes or huge splashes in the steel.  We use hardened steel, but it still seems to damage it.  Also, we've set the minimum at 6mm in the past.  If you REALLY NEED to shoot a 223 you can, although you will be at a huge disadvantage.  Why?  Well, not only is the BC of most 223 ammo low, but you are hitting steel targets called and scored by your teammates.  223's don't knock over the steel like the larger rounds - especially at distance.  So.... you take your chances.

If you insist on shooting it, you must make sure you don't have steel core ammo.  Most any surplus ammo or military is steel core.  If the bullet attracts a magnet it's steel core and you CANNOT USE IT because it will damage our targets.  Please ask if you have any questions!