Darn right they will run the deer off, and no, you cant kill them fast enough. They breed like rabbits. Two years ago, after getting my buck, I emptied 2 boxes of 270 win from one stand in the course of 1 hour just trying to thin out the pig population! When i went out the next morning, there were just as many pigs as before, just smaller ones. If you let them go for too long, you will get into the same situation we did and have a population of pigs that will out-breed the rate at which you kill them and there will be nothing you can do about it.