I might as well put my two cents into this argument.
I am an unabashed devotee of the .280Ackley. Here I should also note that my chamber is the older "wildcat" chamber and not the newer SAAAMI/Nosler chamber.
It is the easiest to load for most unfinicky cartridge most consistently accurate rifle I have ever used.
But it is not a 7mm magnum unless you use top end blue ribbon loads for the .280AI and compare them to the rather pedestrian 7RM factory loads.
A well developed full potential load in the 7RM will outrun the Ackley by a good bit and as the bullets get heavier the bigger the edge to the 7RM.
For my purposes I use two bullets in the .280AI. First is the 120 grain Nosler BT. With 61.0 grains of H4350 I get around 3325 fps and crazy good accuracy from a 23 inch Shilen barrel. Its a near maximum but not crazy hot load.
I have cases that have been fired 10-12 times with no need for trimming or loose primer pockets or any other signs of high pressure even when fired in 95+ degree weather.
Second is the 162 grain AMAX with 58.0 grains of 7828. It is a low to mid-range load that makes 2840 fps out of my rifle's 23 inch barrel. I could probably get another 75 fps or so out of the 162 but I doubt I will bother as the accuracy is so fine and with the high BC of the 162 AMAX 2840 fps will get you a long way downrange in style.
