Your boss was a little blase and you worry too much and expect the world to be controlled by rules.
The best gage is the barrel of the gun. No body NEEDS calipers or case gages or such. They help, but aren't needed.
I always start off testing of a new bullet by determining the max COL that works in my guns. Your boss had to worry about all guns, and the case gage was what he should go by.
Some barrels have rifling a LONG way down the barrel. Others have the rifling very CLOSE to the end of the chamber.
Some people believe that there is a science to COL and they measure the bore diameter of the bullet and have their own idea about how much of the bore diameter section has to be beyond the case mouth.
The best test is to load an inert dummy round or two and determine the longest COL that does not push the bullet into the rifling (unless you are firing a lead bullet at light target velocity), fits in the magazine (or the cylinder), and feeds and fully chambers in the gun.