Bureau of Land Management (BLM) and Forest Service lands are generally open to target shooting outside of populated areas, recreation sites, and other excepted areas. Find regulations for the agencies here:
ATVs, side-by-sides, 4-wheelers and other Off Highway Vehicles (OVHs) can be used on many US Forest Service and Bureau of Land Management roads and trails, in addition to a number of designate state and local OHV areas.