Uneven poles for fence with wood railing?
It depends on the size of the gap. For very small gaps, washers will work just fine. For larger gaps, cut a piece of wood (same wood as the top rail) to shim the gap, and just screw through it. If the gap is excessively large, you'll want longer screws, or you'll want to screw the shim to the long 2x4 first.