rwk said:
Will any of the new powders work in a 6.5 Rem. Mag.
I would not know the answer?

I might tend go with the "old IMR", if IMR is on your mind?! On 1 June 1997, I won the Oak Ridge Long Range Regional (5x1000 yards) using a 6.5 Rem Mag chambered in a Rem 40X single shot and a 28" barrel, with an aggregate score of 987 w/45x. My load was 52.00 grains of IMR4350 with the 144.5 grain Caurtuecio, at around 2,900 fps.
Most likely though, if I were to try that cartridge again; which I won't, I would first try the Hodgdon 4350 and 4831SC powders...they better serve me in F-Class Open than the IMR powders using similar sized cases?
Dan