Kim,
I recall seeing on another forum where a guy had problems with Amaxes, though his were a smaller calibre than yours.
In that case, you could see from the shots he took of the projectiles (seated & pulled) & the inside neck of the case that there was a lot of friction when seating brought about by his neck preparation. The inside of his necks were rough & his chamfering was not smoothly done so there were little dags hanging off the chamfer cut. That looked to be the issue.
On that basis & my own experience, I suspect that Amax brass might be a tad softer than some & the friction between it & the neck higher. These days, I don't have issues because I moly or boron coat my projectiles, so I'm guessing that if your case necks are smooth, some lube like graphite might slick up the seating enough to avoid the problem.
John