Why is it said that the .50 BMG bullet is 12.7mm? Is the bullet

This Ammo Turns Russian Armor into Swiss Cheese — And Ukraine

What is the difference between a 50-caliber bullet and a 12.7mm one? - Quora

Is there a bullet that is bigger than .50 BMG? - Quora

How many times more powerful is the 50 BMG bullet than the 12 gauge bullet? - Quora

What is the diameter of a 12 gauge shotgun shell right before the rim? - Quora

BADDEST Russian ammo you had no idea about - Russia Beyond

If a .50 caliber (12.7mm) intermediate cartridge were made, how large would the cartridge case have to be? - Quora

Is a .50 cal rifle the same as a 12.7 mm rifle? - Quora

50 BMG - Wikipedia