Anyone know where to target shoot in MN?

Tempting as they may be, power line right of way is usually an easement on someone else's property. They may or may not care, as owning the dirt under the power lines is often of little use to them, but it is usually privately owned, and thus you really shouldn't go play soccer or picnic \on it without asking either. Besides - you might be setting up your airgun firing line on the 300 yard line of his rifle range.