Re: What factory ammo to use
For a 1:9 twist, I would recommend 68/69 grain bullets. Some barrels can shoot 77gr in that twist, some not. Match 55gr bullets tend to do quite well at close ranges, as well, and should shoot nicely in your barrel.
For "value" ammo, check out Black Hills Remanufactured and Ultramax Remanufactured. Black Hills is a very popular brand with match ammo, but Ultramax shoots very well for me. Both are around $30/50rds, depending on which specific load you pick.