Generally how long would a gunshot wound to the leg take to heal?

Depends on severity: If it is a small caliber thru & thru wound, not injuring a major blood vessel or nerve, about 2 weeks. Larger calibers cause more tissue damage and take longer to heal.

Depends on tissues: The classic model of wound healing is divided into three or four sequential, yet overlapping,[2] phases: (1) hemostasis (not considered a phase by some authors), (2) inflammation, (3) proliferation and (4) remodeling. If there is still a problem healing the area after 3weeks need to understand where the issue is - 2nd/3rd stage Once the treatment is adjusted wound should heal. Infection is 2nd stg