The .22 centerfires are great out to over 200 yards on 30 lb.+/- critters, but the .243 Win is a big step upward in capability. One day, I sighted-in my new .243 Win, placing a target about 6 feet or so away from a stone wall and fired my first shot. Looking through the scope, there were about 3 holes in the target. Hmm..what was going on? I walked to the target and noticed that the bullet hit rocks behind the target, sending angular stone pieces flying back toward me, piercing the cardboard about 6 feet or so from the stone. I was impressed!!!
Since then, I've fired the .243 against steel targets and it makes a pretty deep pock-marks in the steel silhouette targets at almost 200 yards. The targets aren't high-strength steel, but withstood many rounds of 44 magnum and other IMHSA cartridges without denting.
I consider the .243 Win a capable whitetail deer cartridge (under good conditions) out to a little over 200 yards and several have been taken by the teenage grand-kids and a 130 lb. buck that I shot about 200 yards, while on a mission to carry & set-up a portable blind up a long hill. It's the most pleasantly-surprising cartridge I've fired at game, having killing power much closer to a .308 Win than the .22-250, all three using the same parent case, I believe. Newer bullet designs have also considerably improved this and other cartridges' killing power.