AI AT vs AI AX308 (pre 2014)

Here in the next few months Im going to be buying one of my bucket list guns, and AI rifle. This is a personal rifle for long range shooting and possible PRS type competition for fun.

I talked with Juan at Mile High and he was suggesting I go with the AT over the pre 2014 AX due to something with the action having a bigger firing pin or something like that. I didnt want to take up all his time to go over all the details of what he meant, especially since Im not buying right now.

So what are the main mechanical differences between the two (outside of the chassis differences) and is the AT the better rifle? I like the looks of the AX chassis and the added benefit of the full top rail. That being said, me odds of using those added benefits is pretty slim. However I can get the AT with a Bartlien 6.5 barrel and the AI 308 barrel for the same price as the AX with just the 308 barrel.