Re: Accuracy International rifles.
Sausage, just read through this post and have a few suggestions for you to consider.
The 300RUM is a good cartridge. Consider your game, distance and impact vel when choosing your bullets. Now a days, there are few "bad" bullets, just those designed for different tasks.
Accuracy is paramount. Regardless of vel, BC, magazine ads, the combo you take to the field must work. Decide how you are going to hunt and how far you want to shoot then go try it on paper. Try to balance bullet style with performance and accuracy. If 3400fps won't hit the broad side of deer, try 3100fps or another hunting bullet.
Scope - US optics does make some exceptional equipment. However, a fixed 10X may not work so well in the hunting field. The big thing in hunting is field of view. At close range or a quick shot, the 10X may be too restrictive. Have you considered a variable with a top end of 10X? This will give you more utility.
Range estimation - you indicated this rig will be very flat shooting which means that a longer range shot will be considered. I think most on this board will agree that there is no shoulder fired cartridge that is flat enough to hold on the spine when you are thinking of a long (500yd +) shot. Get a range finder, learn how to use it with a drop chart to match your load.
Match kings to work as has been shown numerous times by other hunters on this board. I am also very partial to the new Hornady SST bullets and Nosler BT for longer range shots. For closer shots, the Nosler Partition, Swift Scirroco and other premium bullets may work well for you too.