Hi, new to the forum. I just recently bought a Remington 700 SPS Varmint. This is my first gun and plan on using it for hunting out to about 5-600 yards. It's a 308 Win and I was wondering what cartridge (bullet weight and brand) would shoot the best out of my gun, and the rate of twist of barrel 1:12 if that is of any importance? Thanks in advance.