Grendel 3 gun?

[Dead Center Miss]

You won't see any noticeable performance advantage with the 6x45 because it doesn't allow loading of higher BC projectiles, but you will be limited on ammunition supply to your ability to load.

From a big picture perspective, there is no distinguishable performance difference between 6x45 and 5.56 NATO.

I have a bolt gun in 6x45, and I'm going to have to disagree with you. I can push a 70 grain bullet almost the same speed as a 22/250 out of the 6x45. Will it shoot flatter then a 70gn in a 223? Maybe,maybe not, but it's going to hit harder.