I've seen rifles shoot an excellent group at 60 yards but then open up a lot, at further distances. Some bullets will hold an excellent group together and then for no reason suddenly the group opens up to unacceptable standards. All you can do is try the different projectiles.

Normally if the rifle is shooting a great group at 25 yards it will shoot groups in direct correlation to that first group as you move back. For instance at 50 yards if it is shooting a 2" group, you can then figure that if you went to 100 yards it would shoot a 4" group or better if the projectile holds true.