I'm not familiar with York county laws, however due to state pre-emption I believe they'll be the same as Sumter county. Here, shooting on private property is completely legal as long as you're outside the Sumter city limits.
I have a 100 meter range out back for private use and nobody has ever said anything negative about it except me when I have to mow it or trim trees. Others in the area have the same sort of set-ups. We all pretty much have guns and horses out here. Being as two sides of my land border a state forest, if there was a problem I'm sure it would have been addressed by now.
The cops seem to have backed that up a few weeks ago when called by the recently moved in "neighbors" (from New Jersey) a mile or so up the road because of gun fire on a Saturday afternoon. They were told to call back when someone does something illegal.