Are you using small base dies for your AR?
Also, resizing other than the neck wears out the brass faster, but you are bringing an AR10 into the picture and for best reliability, you should be using small base dies or dies that bring back to near new size.
Case trimming is more important after using small base dies. For a Semi-auto rifle you are shooting for reliability first, then accuracy. I've never used a head space gauge for rifle cartridges and only the simple drop gauge for spot checking 45 ACP and 9mm.
Typically, a head space gauge is to bring it within a minimum spec and not what your actual chamber is. Chambers typically run a few thousandths bigger.
To the average shooter, the differences between casings means nothing unless you are competing at a national level in 1,000 yard or meter distances. You get a bigger bonus hand weighing each powder charge and bullet sorting to a 0.1 of a grain than anything case related.