My "snarky" comment had to do with the overly long chambering. If someone did use a 9x21 reamer by mistake, guess what? They would STILL label it 9x19.
SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”
It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must be seen as a guideline only.
The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.
This parameter is determined by various dimensions such as 1) magazine length (space),
2) freebore-lead dimensions of the barrel,
3) ogive or profile of the projectile and
4) position of cannelure or crimp groove.
• Always begin loading at the minimum "Start Load".
• Watch for signs of excessive pressure.
• Increase in 2% increments towards the Maximum Load.
• Never exceed the Maximum Load.