the issue is one of VELOCITY all right, with the 223 having 50% more velocity, and also, retaining its velocity better. There is the issue of velocity RETENTION, too, and it's a major deal, A large caliber BLUNT bullet, fights a LOT more air resistance, and thus, slows down faster than does a smaller caliber spitzerboatail shape. Yes, the heavier (for the caliber) bullets DO retain their velocity better than the lighter bullets (for the caliber) if they are of the same shape. The bigger diameter bullet also has a larger "profile" for the wind to push against, (sideways of the bullet) The longer the bullet's flight, the more time the wind has to act on the bullet, ya know. So the slower the bullet, the worse it does against a cross wind, all other things being equal. Of course, all other things are almost never equal, but bullet flight time definitely effects wind drift. It also effects LEAD required, on moving targets,and a bullet that takes a full second to arrive at the target, as vs half a second, ALSO allows the animal more time in which to suddenly take a step, turning a chest hit into a gut hit, (if the shooter is sideways to the critter)
hitting 200m heads is a pc of cake with the scoped 10" 223, without any sort of rangefinder. If you misjudge that range by 10% or if there's ANY wind,you'll miss that head with a 45-70, for a FACT.
