10 sq miles
If what I hear about Texas and their gun laws you might not have to own any land. In Ohio you can shoot a 22 anywhere but not in the city limits.
If you are in a rural-agricultural zone then you can set up a target anywhere on your property. Neither the sound nor the projectile can leave the property. If you are not zoned agricultural-rural you can't shoot anything unless it is hunting season or you have an approved target range.
Other people asked questions on similar topics, check out the answers they received:
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them