Just measure a few fired cases with the Hornady cartridges case headspace gauge and then set the die to bump the shoulder back .001 to .002.

After firing the case springs back from the chamber walls and is smaller than chamber dimensions. This is good because the case can be extracted without binding and easy bolt movement.

This is where the expression "the cartridge case should fit the chamber like a rat turd in a violin case" came from.

Your shoulder bump is the head clearance when the cartridge is chambered. And as long as the head clearance is .001 to .002 on a bolt action, it is well within the elastic limits of the brass. Meaning the case will not stretch and thin in the base that can cause case head separations. Meaning the case can stretch and spring back without thinning in the base.



Below a .303 British cartridge with excessive head clearance with the case stretching and thinning to meet the bolt face. And at maximum military headspace you can have .016 head clearance on a Enfield rifle.



Bottom line, anyone can make a YouTube video, but only "YOU" can measure a fired case and set the die for the proper "minimum" shoulder bump of .001 or .002.