I have my sport .556 and am planning on next black rifle but have questions. I want it to be a "ar" platform. What Advantages are their of .300 over a .556 ? Also .300 compared to .308. What distance can you accurately shoot .300 compared to a .556 ? Is one .300 model more accurate compared to another? Basically I am wanting another ar but want to reach out further distances. Thanks for any and all help