if the rifle will be used for coyote and other small predators or varmints then diffinetly go with the 223.the 223 is a sweat round and its cheap and redaly availible.the 22-250 is also good but is alot harder on pelts and more expensive to shoot.the 243 is also a good round but i will agree with howler,depending on how close the coyote is and where you put the bullet they can be very hard on pelts.don't even concider the 243 for fox.that gun with the 270 for deer and other big game and the 223 for smaller game will be a very versatile gun