I have a springfield M1A and want to shoot it from 50-600 yards. I have an Trijicon ACOG now on one of my ARs so that maybe one of my choices. The one I was looking at was a 5.5X50 and a 6X48. But not sure if thats the way i want to go? I'm also looking at Leupold Mark 4 2.5-10 X 36 and a Vortex at 2.5-10 X44. Can any one tell me what there running I would be gratful!!!