I am having a hard time setting up my scope on my DPMS .223 with a flat top and 20" bull barrel. I think I know basically what the trajectory of a .223 55gram bullet is. When you sight it in at 25 yards to start at the bull it is flat and low. Going out to 50 yards the scope is now raising and high. At 100 yds it is still rising. I set the 3x9 Acog Clone NC Star scope to shoot slightly low at 50 yds and then it will be slightly high at 100 yds. When you come back to 25 you have to raise the scope up to compensate for the flat trajectory. Does this sound right? I have checked this with a second scope I have and it seems to be the way. Am I missing something?