RaceTire/Coyote: Good posts.
A lot of this conversation leaves a huge gap because no one knows what pressures they are actually running,and if we add in the tremendous variations in barrel/chamber/throat dimensions,comparisons between the two cartridges becomes increasingly cloudy.
At the end of the day,over the broad range of rifles,and keeping things as equal as possible the 7RM will always be the faster cartridge,and easier to get higher velocities with because it HOLDS MORE POWDER.
I can build,tomorrow, a 7RM that will show the velocities obtainable from a 7 Weatherby(the 280 AI boys sorta leave that cartridge out of the comparison mix because it easily outruns the 280AI);yet the 7 RM has about the same capacity as the Weatherby,and throated the same, will do what the Weatherby does,......which is,be faster than a 280AI,and the margin will increase as we get to heavier bullets.
Conversely, I can build a 7RM so dumbed down that a 280 AI will likely beat it.
I'll repeat what I said before;someone should take a 280AI,work up to max at a given pressure level,and then rechamber to 7RM and load to the same pressures. I suspect they'll find that the 7RM is faster at the same pressure levels,simply because it holds more powder.
Contrary to what many may think, the 280AI is not spot news,has been around for decades now,and a couple of friends of mine messed with it years ago,and reported results. They don't use it today and think the hoopla over it is sort of funny.I never got involved with it due to having loaded,chronographed and hunted with the 280 and the 7RM since the 70's,and considered the 280AI not worth the bother,the same way I don't understand the 25/06 AI while we have the 257 Weatherby.In both cases, the magnum hulls give you the real improvement over the standard cases without loading to the gills,and still keeping powder consumption and recoil at manageable levels.
Good though the 280AI may be(it IS a good cartridge), if I'm gonna run around with a 30/06-length action and a 24" barrel,I'll take the 7RM everytime.
