The opponents shoot always on the body or on the leg. I agree that some (for example with shotgun) of them are not so easy, but you can make it much easier if you first aim for the head.
I found for both missions an easier way to complete them and would hereby mention two improvements:ġ) In the guide shooting range is given a 10/10 on difficulty. Many people have problems with two specific missions. In order to help you get 100% completion of GTA: San Andreas, I found for two specific missions (Vigilante and Shooting Range) an easier way to complete them.
