Nope, got a 7mm RM that will do everything a .280 Rem AI will do, and then some.
Hmm, looking through Nosler 6 I finally picked up this past week. I see the top 7 Rem Mag load with a 160gr Accubond at
3077 using 72 grains of Magpro. 280AI tops out at
3045 using 59.5 grains of Viht N560.
12.5 more grains of powder to gain 32 fps. Impressive!!
...
If you look a little more closely you will see the .280 Rem AI loads are from a 26� barrel while the 7mm RM loads are from a 24� barrel. Subtract anywhere from 50fps to 80fps, perhaps more, from the .280 for a valid comparison. You will also have to note that different powders were used, making the difference in charge weights pretty much an invalid comparison.
Next, for a more apples-to-apples comparison, let�s compare the same powder using 160g bullets. Since I have and use both and Nosler lists both for both cartridges, let�s use Reloder 22 and IMR7828.
.280 Rem AI
3035fps, 60.5g Re22, 101% Load Density
3043fps, 61.5g IMR7828, 101% Load Density
7mm RM
3015fps, 64.0g IMR7828, 85% Load Density
3058fps, 63.0g Re22, 85% Load Density
If we subtract 75gfps from the .280 velocities to adjust for the shorter barrel, it looks like this:
2960fps, 60.5g Re22
2967fps, IMR7828
If we look at pressure, Hodgdon lists the following:
.280 Rem AI
2849fps, IMR7828, 61,300PSI
7mm RM
2868fps, IMR7828, 58,200 PSI
Looking at all the Hodgdon 160g loads for the two cartridges, it is readily apparent that the .280 Rem AI is running slightly behind the 7mm RM in terms of velocity but at significantly higher pressures. Put another way, loading the 7mm RM to the same pressure as the .280 Rem AI will yield higher velocities.
I don�t know what SAAMI MAP is for the .280 Rem AI or if there even is a SAAMI standard for that cartridge. I do know that its 61,000 PSI for the 7mm RM. I have Rugers chambered in both the 7mm RM and .300 WM and see no reason not to load the 7mm RM to the 64,000 PSI level of the .300 WM. When that occurs the 7mm RM easily outdistances the .280 Rem AI.
By the way Vihta Vouri lists the 7mm RM at 3114fps with a 160g bullet and N560 powder, the same powder used for the Nosler .280 Rem AI load you referenced. That�s 3114fps for the 7mm RM, again from a 24� barrel, compared to an estimated 2949fps for the .280 Rem AI with a 24� barrel. Douing the math, that�s a difference of 154fps.
The .280 Rem AI is a good cartridge, but it can�t keep up with the 7mm RM when other factors like pressure and barrel length are equal.
