Difference in brass size. However since I don't have gauges I will have the smith doublecheck to make sure that there is a problem in the barrel, and not somewhere else. He has the measurements from the AT and can compare to the AT-X
This barrel on the AT-X seems to have more headspace than when it was on the AT, so my brass got around 6.5 thou longer. However I am going to have the smith measure the AT-X and compare with the #'s from the AT so we can see if it was that or some other mistake I made.
...Normally its some mistake I made somehow along the line - either in resizing or something...
Also, I am not a normal AI shooter, normally I shoot a Bighorn TL3, and have shot a few AI's over the years, but none consistently. I have however high hopes for the AT-X since it solves a lot of the stock/chassis problems I didn't like with the prior AI's... Isn't it common for the AI barrels to work across platforms, or is there a lot of variation? I kind of assumed that if they had a swappable barrel then headspace should be consistent across the platforms? Was that a wrong assumption?