I have owned 2 270's, both with 22 inch tubes. Still have one of them. I may have had slow barrels but both of them were pretty much all done at a little under 3000 fps with 130's and 2800 fps with 150's. From reading other postings I am sure that my results were not typical, but that was my experience. Twice.
I like the 277 bore and had lots of Nosler Partitions, 150's and 160's, that I obtained for $10 a box at a sale, so I had a 270 Roy put together. With a 24 inch barrel I have no trouble adding 250-300 fps to anything I was able to squeak out of the 270 Win, and at lower pressures to boot.
Really like the 284 bore also, but where the rubber meets the road there is really very little difference other than what's in your mind. I seriously doubt that a 7 RM or 7 Roy will do anything on game out to 500 yards, which is my self imposed limit, that I cannot do with the 270 Roy.
Opinions vary, mine is that either the 270 or 280 AI versions largest advantage lies in the mind of the owner.
There is a lot of truth in the above post;but maybe some misconceptions, too.There are too many 22" barreled 270's out there that routinely break 3100 fps with a 130,and it has been done by too many people in too many rifles over too many years(very safely)to seriously question whether the cartridge can safely achieve those velocities,especially with todays powders.Yes a 24" barrel may (or may not) give more velocity than a 22" but this assumes both barrels are "equal",and they almost never are.
I have owned more than one 22" 270 barrels that would safely give 3200 with a 130.
I do agree though that going AI is pretty much a waste of time over the standard cases when there are perfectly good belted cartridges with significantly greater capacity.
With bullets up to 150 gr in weight(where 270 cal generally tops out) I could never see the advantage to a magnum capacity 270 over a 7mm...there are so many good full spitzer 7mm bullets out there of 160-175 gr weight,that I feel a mag capacity 270 has little to offer,and this is where the 7mm magnums really trump.There is nothing a 270 Weatherby does with 130 gr bullets that cannot be accomplished with a 7 mag and the same weight bullet.There are no full spitzer bullets weighing more than 150 gr commonly available in 270 that I know of...
BTDT with all these things except the AI's which,to me, are trends that have been hanging around for years,and pretty pointless.I let friends do the experiments with the 280AI and report back....won't waste my time.
On a standard case, give me a 270 or 280 with a 22" barrel and a nice light rifle....if you wanna beat those two, and intend to use a 24" tube,get a magnum capacity 7mm.The rest is fluff.
