Bartlein's #3 is the same as most folks #4 & their #2B is the same as most folks #3. They will recontour your #3 to a #2B in 7mm because they did one for me, they charge $40 if I remember right. You'll have to recrown but they can do it already chambered. I agree with the others not to put a 26" on there, you'll just be adding the weight on there even with a skinnier barrel & it'll mess up the handling, 23" is plenty for a 280 AI. Fluting is mostly cosmetic, it'll take a little weight off but not enough to make a real difference, going down a contour will be a lot more noticeable. At 10# though you likely have other issues like too heavy stock & bottom metal, that's pretty heavy even with a Bartlein #3 contour.
