I have a Rock River Varminter in 223 that is a great shooter. Thinking about adding a Stag Arms #7 upper to it in 6.8SPC. I have the current rifle zeroed with 68 grain ammo and it appears the trajectory of the 6.8 is almost identical. Using LaRue mounts, so might be able to snap the scope off of the 223 and snap it onto the 6.8 without having to re-zero (unless I wanted to get back to dead on zero. But really, really close.) Question is, what is everyone's opinion of the 6.8? Realizing the 6.5 Creedmore and Grendel is a harder hitting round but is it a direct change with the AR15 platform? Thanks.