Hey guys,

I am assuming it is safe to fire standard .280 Remington factory ammo in the chamber of a Kimber Hunter chambered in .280 AI.

I understand that Remington brass is not as soft as Norma or Nosler brass, but also realise that both Norma & Nosler produce .280 AI brass (just a little bit pricey)

yes.
the pressures are the same, and the standard round will HS properly.
Remington cases should form on the first firing, Winchester cases usually take two for a complete forming.

Buying .280 Remington ammo to fire form into .280AI is a wash in price with Nosler brass.

But to answere your question.......yes the Kimber .280AI chamber in the Montana I owned was cut well for fire forming .280 Rem brass to AI

I have a Kimber Hunter in 280AI. I have fired most brands of 280 Rem ammo with 0 issues and the brass is fire formed correctly. My rifle shoots 280AI and Rem ammo equally well and most brands to same POA-POI.

Yes sir, your good to go!

The spec is 4 thou crush fit at base of neck to shoulder. The AI was designed well. No issues at all.

Alternatively . . . since I have a vast supply of .30-06 brass I resize it to create a "false shoulder" for a crush fit in a .280 (or .280 AI) chamber. The fireformed brass is just a tad short of .280 specs, but this simply saves you the task of trimming for several additional firings. The crush fit .30-06 brass delivers exactly the same velocity and accuracy as fireformed brass.

Some people are hung up on headstamps. If headstamps were so important there would never have been such a thing as a wildcat cartridge invented. But if headstamps are important to you (even though you won't have properly headstamped brass even if starting with .280 ammunition), then the '06 brass is not an option.

If your taking two shots to fireform any case your not using enough powder or the wrong powder..or perhaps not fireforming with a bullet and a warm load..I prefer to load a std. hunting load and fire form it if at all possible..I have used that method with the 338-06, 35 Whelen, 257 Ackley, 250-3000 Ackley IMP.

I hardly lose any velocity by shooting factory ammo in these guns to get the case improved, I even hunt with the factory stuff..