PHX area open desert area shooting?

If you don't know anyone local to ask yet..... go visit a BLM office.

You can get maps there (& elsewhere too) and in my experience they're pretty helpful, (At least the AZ BLM offices Ive been too. The CA offices not as much when you ask about shooting). They may even direct you too known areas for shooting.

Dont shoot on AZ State land. Keep to BLM land. They'll butt up against each other at some point.

Another suggestion is when you ask, try to strike up a conversation with them.

A lot of them like that you care about the land they're taking care of and responsible for.

Mention that your not looking for fresh land to shoot up TVs and washing machines... youre just looking for a place to shoot your reusable steel targets (Pack it in and pack it out) that isn't too crowded with dirt bike riders.