@Reloadron,
I found the PTG and forster gauges to be dead on up to 1/2 thou. because that is the best I can do and I don't need more precision.
The question is, isn't the RCBS mic design prone to misreadings or being off because of the threads or bushing?
In any case, it is a pretty common practice to headspace using the loads we are going to shoot, many times Federal gold medal or Lapua.
When reloading, the shooter's goal is to replicate the factory loads both in terms of dimensions, speed and accuracy.
People tune up their reloads so we end up with consistency whether one uses custom loads or factory ammo in those places that might not allow reloads.
I follow the same precise brick and mortar directives. Some BR rifles might require a chamber for a unique reload and bullet.
I sill don't get why would anyone return gauges of different brands and measures. A go gauge of 2.631 is not because it is a mistake but because they
choose to stay with a larger lower limit as per SAAMI to make sure any kind of ammo would chamber. Actually in the case of the 308w 2.631 or 2.632 is
just about right for a good chamber.
Different gauges or entire sets are used by master gunsmiths all over the world including the ones who make match winning rifles.
This is a fact whether we agree about other methods or not.
I think we all agree the end goal is to have two parts to come perfectly together with minimum tolerances.
Perhaps others who chamber match grade chambers and rifles want to chime in.