Ah. I know the area you're talking about.
The problem is that it's right on the border or BLM and State Trust Land. The hill is BLM, the land north of it is State Trust. So technically you'd be shooting on State Trust Land with your rounds landing on BLM Land.
Questionable if that's legal. Realistically you could probably get away with it, but if someone wanted to give you a hard time, maybe even fine/jail you, they'd probably be able to.
-T.