The .243 WSSM from Oly looks interesting to me too, but I agree with az-ar. There are plenty of accurate, proven, and relatively inexpensive uppers in .223 that you could use to do battle with your father-in-law. There are also lots of load data, books, articles, and other information on making .223 AR-15s shoot well. I think going that route would simplify your task and save you time, money, and aggravation. I also agree with simonsay that higher BC bullets are the way to go at long range. However, if you two conduct your shootoff at three hundred yards or less, this isn't so critical. Either way, there are lots of good match bullets out there for the .223, expecially the relatively new heavier bullets with high BCs. For a scope, I think you should get a variable in the 6-18x range. I wouldn't get a high fixed power because conditions like limited light and severe heat shimmer can make you want to turn down the magnification. - Just some thoughts.