I think the 264 Win mag is a great caliber. It needs at least 26" of barrel and longer is better. If you plan on shooting 140 gr bullets you need to get an 8" twist in the barrel. The barrel will not last you long if you want to do a bunch of target shooting but for a hunting rifle it will last you a life time or two if you don't heat up the barrel a lot and treat her right.
I have a Rem 700 with a Shilen chrome molly #4 that is 27 3/4" long, all that could be gotten out of a 28" blank, 9" twist barrel. With 66.5 grs Retumbo powder, CCI 250 primer, WW case made from 7mm mag cases, 130 Nosler accubond I average 3350 fps and it shoots 1/2 MOA. You can make 264 mag cases by simply running a 7mm Rem mag case into your full length 264 mag sizing die.
My hunting buddy had the rifle made up for bean field hunting in east NC for deer. I had something he wanted more and we traded.
I have not had the rifle but for three deer seasons and I did not kill a deer with it last year do to limited hunting time. I have killed 7 deer with it and only one took a staggering step before it hit the ground dead. The others dropped like the ground was jerked out from under them. Shots were from 80 out to 400 yards.
I have a friend that uses the 264 win mag for everything up through elk. He uses one load. A case full of the old H-870, of which he has a good stash of, and a 140 Nosler Partition. He said that he has never had to shoot anything more than once with it. From what I have seen from the deer I have shot with the 130 Accubond if I ever got the chance to elk hunt I would not hesitate to use it.