Thanks for posting this comment. This is right up my alley, since I'm working with a standard 280 Remington and the Hammer Hunter 143 now. I had planned to start with H4350, after discussing it with the guy who makes the bullets. I had called him about whether or not I could use something heavier, to which he responded that the 143-grain HH is the heaviest bullet that would reliably stabilize in a 1-in-9" twist, and I should expect to get velocities right around 3100 fps. I also asked him if I should stick with what I had learned years ago while working with a bullet in the 7mm Remington Magnum that also had a relieved bearing surface. With that bullet, a slightly faster powder for the bullet weight worked best, and he told me that this also applies with the Hammer bullets. Not a lot faster; just a little. He also mentioned that case-fill makes a difference, and that I might want to try the slower powder I had mentioned to him ( H4831 ) if I don't like what I get with the 4350. Lastly, he recommended magnum primers. He mentioned in an answer to a question I had posted on this forum that these bullets work well with the Lee Factory Crimp, and to crimp in the first groove nearest the nose of the bullet. Any more comments you might have for the 280 would be greatly appreciated.