I have unrelated experiences that are all over the map.
Bought an aftermarket BBL for my Glock. It had NO throating at all. The rifling lead right up to the chamber cut. It was a PITA, and made for shorter COALs than were necessary or really advisable for the chambering.
FFW to last night's experience:
I have an old Ruger M77 in 22-250. It is a tack-driver of a rifle, and an old favorite of my Dad's, who had it given to him as a gift on completion of a special project long ago. I inherited it when he died, in 2002, and have shot it some, and loaded for it, but never really looked at it critically.
Last night decided to find out what kind of leade was in the throat. Neck-sized a cartridge for it, and just finger pushed a bullet in the neck far enough to stick there, then chambered & closed the bolt. Opened it and measured the COAL. 2.460"
SAAMI spec is 2.350" for the 22-250. I don't really care if I go outside the lines a bit on COAL, but there's no more than a diameter of bullet in the neck. Seems really long to me. I looked the throat over real close to see if it might be shot out, but it is bright as could be, so don't think it is eroded.
What do y'all make of this, and how much attention do you pay to bringing the ogive of yer boolit to the throat of the rifling? I realize that pistols are going to be different than revolvers, which will be different again from rifles. Autoloaders will have to have a bit of leeway that bolt guns won't need.
All in all, a very inexact science for such a scientific thing, it seems like.....