I love my 280AI but I picked up a 7 SAUM so i could make a 6.5 SAUM. Problem is I shot it and it is a fantastically accurate rifle and now I feel the need to shoot it until the barrel is toast and then downsize it .5mm.
What you are hearing is true, those two rounds are interchangeable for speed, just different action sizes. The once thing about the 280 is you can use standard 280 rem brass and just shoot it and they fire form, SAUM brass is pretty rare right now, and the prices it is demanding is ridiculous, just look at gun broker and other places. The nosler stuff, when you can find it, is $50.00+ for 25 pieces.
