Re: 6.5 Creedmoor VS. 308 for big frame AR build
I have discovered over the years, picking up brass shot from a semi-auto is not as easy as I lead myself to believe. I lose some here and there, and if I had to recover .260 brass, I would be really pissed if I could not recover them all.
Semi Auto's burn barrels faster because the urge to go bang bang bang bang bang is there. Even from a bolt gun, a .260 barrel has about half the lifespan of a .308. With semi auto it will wear even faster. With a .308 it's like you are getting 2 barrels.
Semi Auto brass also has a shorter life than bolt brass. For .308 AR's you probably could get 10 reloads from one case with lighter loads, not sure if you can say the same for .260. With .308 LC brass, I have necksized the same cases 10 times now and they are still going strong. I am thinking 20 reloads easily from one case (necksizing for bolt gun). For my AR10, I have only sized (full) the same brass 5 times (but I am thinking they can probably go 10 easily).
For a match shooting bolt gun, .260 is the easy choice over .308. It has about 10 MOA less drop at 1000 yards, and bucks the wind about 4 MOA better at 1000 yards (10 mph). A flatter trajectory will always be more accurate if you have to range your target. However, once you confirmed the distance, a .308 can be just as accurate. If there is no wind or the wind is consistent, then the .308 is capable of being just as accurate. However, every little bit helps, and the .260 does give you the extra bits.
For an all around semi-auto AR, I would chose .308. Brass is cheap and in abundance, barrel lasts longer, and you can shoot other people's ammo.