You missed my point. With light bullets that are suitable for the standard slow rate of twist that .22-250s ship with, the .22-250 is a terrible long range cartridge. It shoots pretty flat, to a point, but it lacks in the BC department which means that it gets blown around in the wind. Drop is easy to compensate for and at a known distance, it is essentially irrelevant. Wind drift becomes everything at that point. With the 1:14 twist that the Remingtons ship with, you're fairly limited on bullet weight.
Comparing the 53gn Vmax (best BC available) from a .22-250 (which some guys have had trouble stabilizing, but we'll assume that this particular rifle can make it work) @ 3700 fps and compare it to a rather mundane .308 load actually suitable for 500yd+ work (168 Amax @ 2600 fps), the .308 load exhibits nearly 3" less wind drift at 500yds and by 800 the difference is over a foot. Figure in a 208Amax at 2450fps and the difference in drift goes to 28.5". And again, the .308 is hardly a good choice at this type of distance. The .243 with a 107 SMK equals the above 208 Amax load with an easily achievable 2900fps and significantly less recoil. That bullet will work in the available barrel twist for the American as well. Sorry, for intermediate to long range work in an off the shelf rifle, the .243 is going to be the superior choice.