I guess I should post this here instead of reloading.I am just starting out with this cartridge,I have the nosler #5 manual.Rifle is a 26" tube MDL 700.RB

I got a 5% increase powder capcity. I use H4831Sc with a 150 B-tip for fireforming. I cut back a grain from listed max. With Norma brass 61.5 grains is max with a 140 Accubond. 62 will flatten primers. Increase max on the standard case by 5% on paper and it should put you very close to max load for load work. Start at max 280rem loads on formed 280AI brass loads and work up from there 1/2 grain at a time. H and IMR 4831 has worked excellent in 4 280s now. I use it with Fed 210Ms and a plastic tipped bullet with great results.

The .280ai is slightly overbore & works great w/ slower powders. My .280 thrives on IMR7828, 59gr under a 140gr bullet. 7828 runs about 100fps faster than H4831 for equal pressure.