Or.... you COULD go to jail.

It depends on the situation.
I live in the city limits of Wilson, NC.
If someone decides that they want to do a little plinking in my back yard, they will regret it.
The neighbors would call the police, and the police dept would arrest you for discharging a firearm in the city limits.
Then I would press criminal trespassing charges against you.
The charges that the police filed would be because you discharged a firearm within the city limits.
However, my charges would be criminal trespass charges because you invaded my property (posted or not) and decided to do a little target practice. Don't know for sure, but I'd bet that I'd win.
Why does it matter that I own a small piece of property, or 10,000 acres?
It's still my property, and you have no right to use it for target practice, without my permission.
Now, if I had 10,000 acres out in the boonies, I would probably let it slide, and just tell you not to do it again. But then again, I MIGHT NOT.
I might be a hateful SOB and want to see you go to jail.
In reality, you'd probably not spend a lot of time in jail, but you MIGHT have to pay big lawyer fees, fines, etc.
So why risk that?
All I'm saying is that you need to either get written permission from the land owner, or go to a shooting range.
Otherwise, you're taking your chances.
Good Luck,
Duane