Thinking about building my first varmint/predator rifle. I'd like to see 1/2 MOA accuracy and CLEAN kills on coyotes at 300 and 400 yards. My first thought was 243 Win, perhaps AI, in a Remington 700 with heavy Shilen barrel. But I've become interested in 6mm BR. What are your suggestions for round and rifle? I will reload, prefer a heavier rifle, maybe thumb hole type stock.