I am looking for an optic for my AR15/.556 18in gun and I just got it... I love it actually. I currently have an acog on it and that just doesnt ever seem like enough. I am looking for something that is adjustable 1 to 8 maybe 1 to 10 power something that I can get more distance out of. I have been looking around and the only thing I can find is the Mark 8 which is like 4k almost... is there anything out there? What do you just recommend.