For most non-magnum hunting rifles, 2" high at 100 yards will put you pretty close to "on" at 200 and around 6" low at 300. With a .308 and the 180-gr, you'd be a bit lower than that, but not enough to worry about.
This sort of sight-in means you can just "point it and pull", with no particular worry about hold-over, or "Is he 150? 200? Duh?"
Obviously, if you already know you'll be shooting at under 150 yards, you'll do just fine just as you are.
Go practice! And not with a benchrest! Milk jugs and soda cans at 50 to 75 yards, off-hand and sitting, for instance.