So I built my A.R. with the intention of it being a tactical gun. As I got into it more I realized I wouldn't be happy unless I could reach out there at least six hundred yards with it. I talked to one of my local gun guys and he said on the 5.56 platform in his opinion said the 6.5 creedmore. I'd like to stay with the same size round for both uppers (I decided to build two) but if the 6.5 is better at distance so be it. Here's some pictures so you can see how the direction has changed.