A .260haswhat? 17 thousandths of an inch of "margin for error" over the.243. That is so miniscule that it is patently ridiculous to argue that it has an advantage.
This is the difference between a .243 and a .260
time 0-250
velocity 0-250
energy 0-250
.243
t= .26 to 250 yards
V= (0) 3127- (250) 2527
E= (0) 1953- (250) 1303
.260
t= .29 to 250
V= 2896 - 2396
E= 2233-1533
As you can see the .243 is faster than the 260 but the 260 has 280 pounds of more muzzle energy and 230 more at 250 yards. So that 17 thousandths margin that you speak of does make a difference. This is shooting a Remington Ballistic tip 90 grains in the 243 and 120 in the 260. Of course the heavier bullet will have more force when hitting your target and the smaller bullet will get there faster. This proves that but, what else does this prove? It proves that the largest grain for a 243 is 100 grains and the smallest for a 260 is 120. This results in the forgiveness that everyone speaks about. If you were to check into recoil the 260 is about the same as the 243 and 7mm-08. It is a little more (maybe 1/2 to 1 pound) more than the 243 and less than (about 1 to 2 pounds) the 7mm-08. I am not lobbying for my choice as you said, I am mearly stating the facts as I found them when I was looking to do exactly what this guy is doing. As far as learning to shoot why not let her learn with a 22 instead of a rifle that has 2 to 3 times the recoil of it? I never have understood why someone trys to teach a child how to shoot with a shotgun or a rifle other than a 22 or 17.