I find this discussion interesting from the standpoint that all three are highly capable out to the 300 yard mark the OP stated. If one is really set on using energy to evaluate the effectiveness of a round then you should pick the larger bullet. The reality of this situation is that there is not much difference between these three and the answer will come down to personal preference. Recoil is limited with all three and trajectory isn't much different out to 300.
Ammo availability is big advantage to 308 but there are some good options for the 260 as well. The 7 mm and the 260 will just not have the options but I tend to like those two better than the 308. Again just personal preference.
Ammo availability is big advantage to 308 but there are some good options for the 260 as well. The 7 mm and the 260 will just not have the options but I tend to like those two better than the 308. Again just personal preference.