The reality is that a factory rifle may or may not shoot really well. The chances of a semi-automatic shooting really well are poor.
243 is an overbore cartridge that has poor barrel life, and unless you ARE shooting varmints, there would be no real benefit over what you already have. If you do not already done so, I would strongly encourage you to invest in reloading equipment. You will never trach a point of really good precision using factory guns and factory ammo. (I say this as this is the precision rifle forum).
Reloading will extract that much more accuracy out of what you already own, and ultimately upgrading the barrel of either your 223 or your 308 in combination with reloading, you will achieve the ultimate in precision results.