the 260 , out to 1000 yds, is about as good as it gets, if limiting yourself to 600 yds., the only thing better would be something 6-ish, if handloading, the 260 is expensive off the shelf. A nice 6x47, or a 6ppc, or 6br, or even a fat 105 or 110 grainer, in 243, would do a nice 600 yd shot.
and of course, if you wanna go straight factory rounds, or milsurp, you can allways go 308.
I just looked on another page, about a dude testing his son's 243's, with 26 and 28 inch bbls, using a new powder called 100v. he is pushing 95 grain berger vld's at 3350, and 3450 fps, respectively, and shooting groups were between .2 and .4 at 100m. that is freakin amazing!!!
