Firstly I'd get an invisible fence for your dogs. If they roam onto his property then there isn't anything that you can say about his running free. You can probably run a pretty big perimeter around your yard so that they can still provide adequate security for your outbuildings and the like.
Then you get his dog a collar for your fence. If it tries to get across it will get shocked. Eventually it will learn the perimeter. It costs you some extra money but resolves the problem. Heck he may even pay for the collar.
If a dog comes into my yard they get stung with a BB or pellet. If they come in an get threatening to me, my wife, our animals, etc... Things get a little more serious. And a .22 isn't reliable to take down a dog.