Hi there, I study Terminal Ballistics as an occupation which runs alongside my Guided hunting business in New Zealand. I thoroughly agree with the advice given from other posters about the Amax. I wouldn't mind just adding to these posts a little more about my experiences with the 162gr Amax.
At 280-7mm mag velocities, I found the Amax to give acceptable kills at close range but nothing fantastic. The Amax is too soft for Boar at close range and may fail to penetrate heavily shielded shoulders.
The Amax really comes into its own at velocities of between 2650fps and 2100fps ( between 200 and 600 yards from your .280AI) At these ranges, kills are spectacular, mostly because wounding and bleeding can be easily seen through the scope which provides instant feedback.
In my tests, I tested the SST alongside the AMax to see how these bullets could be used together. The SST was definately superior as a game bullet at high velocity close range impact but as velocities approached 2600fps, the A-max killed considerably faster and created far broader wounds. Performance of both of these bullets differs from the Nosler BT.
Off the subject a wee bit, I once shot (culling) 16 goats off a ridge one evening using the 6.5x55 and 140gr Amax. Muzzle velocity was 2800fps, range of animals was on average 400 yards, impact velocities averaged 2300fps. Performance was absolutely awesome and every animal went staight down, as animals rolled over both exit wounds and bleeding could easily be seen. Its such a shame that Hornady do not make the Amax in every calibre regardless of whether each calibre has match shooting merits.
Good luck, sounds like you will have a lot of fun with your rig. Have you established an optimum throat length to be cut for long for calibre bullets?. My wife's .280 gives best results with powders in the 4831 buring range, the rifle will achieve top velocities with slower burners but accuracy falls off a wee bit.