I don't know of any county in OK that prohibits someone from shooting on their own property, as a matter of fact I'd say it is very unlikely they would not allow it. But I'd recommend calling Adair County Sheriff's office and ask them.
Shouldn't be a problem but as stated would contact Sherriff's office for confirmation. And just a reminder know what's beyond your target and have a sufficient backstop. There want be any issues till and if projectiles start leaving your property and that can open a can of worms you do not want to deal with. Beyond that BE SAFE and Have Fun!!!