If you are considering an additional upper, in a larger cal, you may want to consider the 6.5 Grendel. Its performance is nearly that of 308 and they say recoil is about 1/2 of the 308. It is a really "up comming" caliber and holds some very good potential. It appears that it has about the same ammo availablity as the 6.8, and is much more capable than the 6.8. Wolf is even making the 6.5 Grendel (Gold line), not sure they are making the 6.8, that will help in keeping the price down and making it more available in the future. The uppers are about the same price, so it is more a question of caliber and desire.