It's funny how the head spacing differs on each action. I was messing around with some barrel swaps the other day before I executed the actual plan and the HH barrel I just purchased from another member lines up the irons perfectly when head spaced on my Shilen DGR Action, but is like 30-40* off on my M10 using the same gauges and everything. Also had to retime my APA brake on my 243 barrel when I moved it from the M10 action to the Shilen Action even though the same headspace gauges were used.

Just because I'm curious can someone with a better background in the machining world explain why this is? You would think using the same gauges would line a barrel up the same way on each action you headspace a barrel on.