CMMG Bull Barrel upper questions?

[ksmith13]

I purchased a CMMG Bull Barrel upper to see what kind of accuracy I can get out of an economical AR style gun. It is a 1/9 twist, what weight bullet would you reccomend I can only shoot 100yds here at my house but have access to a 600 to 800yd range that I will shoot at when I get it sighted in. Thanks in advance
edited for spelling