Excellent thread, good stuff. So, I've been a silhouette shooter for some 30 years now. We first shot 308s and got beat up. Then the 7mm 308 wildcat was the rage and Remington introduced it. I burned up barrel of 7mmx308 on silhouette and game at 7500 rounds.
Then the attention was directed at the 6.5mm. There was great experimentation because the 140 gr bullets would take down rams and the 120 or 107 would take down everything else with very little recoil. The 6.5 BR, the 6.5x250 Savage ( take note - the 6.5 Creedmore! ) , the 6.5x308 (260 Rem), the 6.5x55, even the 6.5 TCU (6.5x223) among others appeared. I went with the 6.5x308 because of brass components avalibility. Here is the most significant statement about all this. Within 400 to 550 yards, there is no discernable difference between all these cartridges. No game animal will be able to tell the difference between a couple hundred feet per second. I will add that I have also burned up a 6.5x308 barrel on silhouettes and game at 7800 rounds and have more thousands in the pipeline with other rifles.
The 6.5 cartridges are fantastic for being the beautiful combination of low recoil, flat trajectory, minimal wind drift, high penetration, deadly performance. My 6.5x308 rifles have given me great satistfaction on appropriate game.
If you shoot any 6.5 you will probably find it to be a favorite. It certainly is mine.