I am not a gunsmith, so I cant give detailed particulars, but when I ask for a rifle to be throated for a 105 A-Max (as an example); I want the bullet seated so the base of the bearing surface is just ahead of the neck/shoulder junction and the forward part of the bearing surface is just slightly back off the rifling at that same seating depth.
This may have other meanings to other folks, but that's my general interpretation of what "throated" means. Others may want a .020 jam with a VLD and same seating depth.?
No, I didn't mean that close of tolerances. I would want to be able to seat the bullet out to touch the rifling without it being 1/2 way down the neck, and likewise; I'd want to be able to seat it back a little too and not have it take up too much case capacity. I would want to be able to adjust seating depth a little both ways with that heavy bullet.
I'd rather have it too short than too long, because the throat will wear out as we shoot it. Also, If we throat it short for the heaviest bullets we intend on using, then it's still OK if we decide to try some lighter/shorter bullets. Last thing I personally want is a brand new rifle that I can't get bullets out to the rifling in. Even though I asked for it throated for 105's, I may end up shooting 80's in it too.
Again, this is just me. Others may have other preferences.
It will depend on how the person orders the reamer or asks the throat to be cut if done by hand.
The reamer mftrs can take a case and a certain bullet and cut the reamer so the bullets ogive just touches the lands with the base of the bullet in a certain point. Some want the base of the boattail at the bottom of the neck etc.
The gunsmith can use a throater to cut a certain depth throat if the reamer is shorter to lenghten it for a longer bullet.