Because the minor diameter of the barrel is 5.56 mm and the major diameter is 5.69 mm. If the bullet were smaller than that then the propellant would blow past it. They didn’t make a 'murican millimetre like they did with the imperial system.
I would make a bet that more mass shootings are done with 9mm. Depending on which shootings they consider ‘mass’ I see estimates from 60-80% for handgun usage. I’m sure the cheap .22 is a large number, but 9mm is probably right up there. There is a large bias in reporting the school shootings and shootings involving rifles by the media. They almost ignore the others.
9mm
We’re more familiar with 5.56x45mm thanks to all our school shootings thank you very much.
In the same way a US ton and a metric ton is like 10% different, a 556 bullet is actually 5.7 mm across.
Because the minor diameter of the barrel is 5.56 mm and the major diameter is 5.69 mm. If the bullet were smaller than that then the propellant would blow past it. They didn’t make a 'murican millimetre like they did with the imperial system.
I would make a bet that more mass shootings are done with 9mm. Depending on which shootings they consider ‘mass’ I see estimates from 60-80% for handgun usage. I’m sure the cheap .22 is a large number, but 9mm is probably right up there. There is a large bias in reporting the school shootings and shootings involving rifles by the media. They almost ignore the others.