most predator calls on the markert will call in a fox, but fox, in my experience, don't come in like a coyote will, they will be abit more sneaky in thier approach, not as sneaky as a bobcat, but they aren't as bold as coyotes are. Using you 22lr, is a bit on the lite side in my opinion. It will work at close range, and yes a double lung will work, but I'll bet he still runs a ways before going down, so ya might need snow on the ground to track him down, as there won't be much of a blood trail. Good Luck!