There should always be a quick-release or breakable component to cross-ties, in case the horse panics. The simplest such device is to put a loop of twine at the top. The twine will break if heavy sudden pressure is exerted. However, any heavy metal element, such as a large metal snap, should be placed at the halter end of the cross-tie, not at the end of the tie that attaches to the wall/twine. If the horse breaks free, you don’t want anything heavy flying around at the end of the rope that’s still attached to the horse’s halter and could hurt the horse or anyone nearby. For the same reason, metal chain should not be used for cross-ties.
Place the heavy snap on the horse end of the cross-ties.