Caliber selection

[Tomas204]

I'm building a gun for long range shooting and predator hunting. I'm mostly going to be handloading, it doesn't really matter if I have to fire form. I was thinking a 6mm or a 6.5, the 6mm because I like the variety of bullets, and the 6.5 because my brother has one and he gets sub moa groups with his. The calibers I was leaning more towards is 6.5 rsaum or 6 rsaum I've never heard of a 6 rsaum but I was wondering if it was any good if anybody has even done it. I'm open to suggestions

 

[jakelly]

I really like the 6 creedmoor, 6x47 Lapua, 6xc, and 6SLR cartridges for longrange varmint hunting and "havin fun" long range shooting. That 6.5 RSAUM is awesome, but brass is very limited. If I wasn't going to use it for a dedicated big game or competition rifle I'd stick with the 6s.

 

[Crosshair]

How bout good ole .243? The Ackley improved would be great too.
Good read here: .243 Win + .243 AI Cartridge Guide