I'm looking at the .280 AI and found Norma, Remington, and nickled Winchester in .280 Rem.
Or would it be better to start with some really fine 30-06 Lapua or National Match brass?
What do you guys like to us use?
I think to some extent it depends. Is the rifle you are contemplating going to be heavy barrel, super accurate job or a hunting rifle? If it's going to be a hunting rifle, I can't see the need for the extra expense of Lapua or National Match brass. In fact I'm not too sure I see the need for it regardless in anything less than a bench rest rifle.
I have a 280 Remington but not in the AI configuration. One of my '06s, however, is in the AI configuration. The 280 Remington, a Browning Medallion, will shoot into less than a minute of angle at all ranges out to 300 yards. The '06AI, a Winchester M70 Classic, will do MOA or a little over at all ranges out to 300 yards.
The only reason I mention the accuracy potential of the two rifles is that I use Remington brass in the .280 and mostly Winchester brass in the '06AI. I've tried a small lot of Lapua, Norma, National Match, and Federal in both rifles with various loads and saw neither an increase nor decrease in accuracy of either rifle.
I don't go to the bother of weighing and segregating the brass either, but I do fire-form, trim to a uniform length, uniform the primer pockets, and deburr the flash hole. I also seat the bullets with an RCBS precision seating die; however, I resize with either the precision sizing die or a Redding neck sizing only die. Use the Redding mostly and FL die only when I need to bump the shoulder back a little.
To me a little care exercised in first and subsequent case preparation, determining the best seating depth for each bullet being used, and care in the loading process will go a long way toward making accurate loads. I think one will generally gain more benefit from this than buying some high priced brass.