If you buy any of those I would love to go to the shooting range with you. The way I was told is the ACR has a higher rate of fire than the scar. The scar shoots 7.62 correct? I thought the acr shot a smaller round but I cant remember exactly. I still would love an bushmaster AR15 platform to build off of. Another small rant is why do ACOGs have to be sooooo expensive? They used to be quite a bit cheaper if I remember correctly.