Like the two posters above said, take a look at the Leupold VX2 4.5-12X. I have some very expensive glass on some rifles, and I just put one of these scopes on a 5.56. I love this scope! For the money, it is a great scope and very bright. On top of that, I sent Leupold all my load data and just yesterday I got the custom CDS elevation turret knob that they'll give you for free with that scope. Now I simply dial in the distance of my shot.
Granted, you're saying you'll leave your scope set on a lower power, which is also fine - it's a bright scope, it's not real heavy and it will give you the option of reaching out there further sometime in the future if you want to. Just leave it set on 4.5 in the meantime.