When I looked at the 6.5,s I chose the 260 rem AI for many reasons.
I had plenty of good 7/08 and 308 cases (Lapua) and felt it would be the best way for me.
I am a big fan of the Ackley,s and it seemed to be the right powder volume for a good 6.5 hunting round. With that said, I chose a 1 in 8 twist 3 grove barrel (For a little more velocity and longer throat life)
I also chose a 24" Sendero contour. the action I chose was a Remington 788 because of the center feed feature.
I did a traditional AI chamber using a 260 head space gauge so i could fire 260 ammo if need be. The rifle will stay just under 1/2 MOA while fire forming and in the fired cases 130 grain bullets will go beyond 3000 ft/sec and the 140, s are just under 3000 ft/sec. With the right load and barrel the AI will produce 100 to 150 ft/sec more velocity.
The 788 Magazine will take a COAL of 2.815 with space to clear, so I load 2.815 and seat bullets that will allow some freebore. case density is at 95 to 98% with the best powders so I don't worry about compressed loads with the 140 grain bullets.
In my opinion there are no downsides to the 260 AI and the fact that in a pinch you can use 260 Rem ammo that has equal or slightly better ballistics than the CM. and the fact that Lapua Now makes cases for it, I feel you are making a wise choice. Mine seems to realy like the 129 grain Accubond with the best 5 shot groups to date just under .200 thousandths and will realy send them fast and flat.
Just my opinion on twist and Barrel length.
J E CUSTOM[/QUOT I have a 260 Rem and a 6.5 Creedmoor. Reload for both. I get like 250 FPS more with the 260. Same 140 grain bullets. My Creedmoor sets in my closet next to my 300 WM collecting dust. My COAl is at 2.820 on the 260. I can set it out to 2.840 but it has feeding problems. My Accuracy International mags inside diameter is 2.851 and another mag is 2.853. On the Creedmoor The body of the brass that can hold the powder is only 1.490 and the 260 is 1.560. That is a pretty big difference on power capacity. If I change my action to a medium action for the 260 I can set my COAl to 2.990. The 6.5 Creedmoor can not even come close to this. The casing is to short and the bullet is all ready at almost max COAL from the Factory. Thats the way it was designed. Hornady was trying to make a factory bullet that was accurate and did not need people to reload for it. I can get around 2700 FPS from my Creedmoor with the 140 grain VLDs But I get 3020 FPS with the same bullet in my 260 Rem. My COAL on my Creedmoor is just like the book says. max COAL 2.800.I can't set it out much longer cause the bullet will fall out of the neck. Hornady pretty much nailed it for people who don't like more know how to reload. If I did not reload I would shoot my 6.5 Creedmoor.
