Josh. If you are able to sidestep with any speed at all( ie. you don't have some physical impairment) , you can easily step behind a tree, or climb one to get away from wild boar. Boars get scared when threatened and their main choice of defense is to run away. You have to be careful that you are not standing on their chosen escape trail.
Unless you insist on take frontal brain shots, there is no need for any high powered rifle to kill boars, no matter the size. If you look at the location of the brain in a pigs skull you will see that there is a lot of bone in front of the brain. Its the worst angle to shoot a hog!
Hogs hang out in the woods. That is where they root for food, and their large eyes don't take to bright sunlight very well. Their eyes are also located on the sides of their heads, making them a prey species, who uses it speed to run from predators, rather than having binocular vision to attach them. They do see as well with their eyes as humans, except that they don't have binocular vision as we do, and therefore have to look forward with only one eye by turning the head to the right or left. Because of this one-eyed vision, they are not very good at depth perception. They look under brush, at the stems and trunks, to determine the location of obstacles, and not up and over the brush and small trees. Corner a boar, and he will try to go through you if that is his way out. But, it is kind of hard to describe that as a " Charge", which suggests an intention to do you harm. Even a 400 lb. boar stands less than waist high to an adult man. You are a giant to him, and he wants nothing to do with giants! And, trust me, he has never weighed himself to find out how much he weighs, nor has he figured out that he can easily overcome and hurt or kill a human being if he wants to do so.
Use your ML and have that fun experience, but pick a better shot than hitting him in the forehead. If you can't get a better angle, WAIT. Another time will come. Hunting is not "GETTING". If it was, they would call it " GETTING!"