Quote Originally Posted by LoneWolf View Post
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.
it would have to do with the cut threads inside the action will be different from action to action. Even a small difference will create a difference in barrel alignment. The headspace itself will be the same tolereance range rifle to rifle BUT the barrel alignment will be different which is why brakes and iron sites tend to not work so well for doing barrel swaps