SAMMI 280 ACKLEY IMPROVED CHAMBER LENGTH QUESTION

[L.Sherm]

I could be wrong but according to the SAAMI prints he posted, to me it appeared the 280 Rem rad is .125" and the AI is .06".

At the neck shoulder junction?

 

[L.Sherm]

The 280 Rem brass is longer at the neck shoulder junction so it acts like a false shoulder when you fireform brass.
I know smiths use go guages for no- go on AI chambers too

 

[Roughrice]

To the OP

My guess is one chamber is close or at SAAMI minimum and the other is at the middle of the tolerance (+.005")

I would do as suggested and face the breech end of the barrel for additional set back but use a head space gauge not a case.

Did you confirm the interference is the bolt lugs and not the nose?

No, I did not confirm.
I just felt a hard stop resistance while resetting headspace, removed the "go guage" and felt the same hard stop.
Jams the bolt with empty chamber and still too long.
At that point...I just stopped, threw things around and cried a while!

 

[Pdvdh]

It appears as though you did not take into account the difference in the radius at the neck shoulder junction between 280 REM and 280AI. The larger radius on the 280 REM contributes to the "crush"

The difference in headspace, as headspace is defined, is 0.014X". The SAAMI headspace being shorter.