smokepole,
No, I haven't, but I intend to, as I'm in the process of putting together another .280 AI. I also intend to try IMR7977, as it's very close to H1000 in burn rate, and Hodgdon lists it as getting a little more velocity. Have been using both powders a lot lately and am becoming very fond of both, but need to pick up some more H1000. Luckily it's becoming more available again.
What I normally do when trying handloads for an article is search all the available tested data for powders that produce the highest velocities with different bullet weights, and also those listed as most accurate. Evidently H1000 didn't make my list the last time I tested a .280 AI, and IMR7977 wasn't around yet, but am going to change that with this rifle.
Over the past couple years have found H1000 to work great with some other cartridges from the .223 WSSM to .300 Winchester Magnum with 180's. IMR7977 has also been very impressive as well, especially with 150's in the .270 Winchester, another indication it should work great in the .280 AI with 160's.
