Can you shoot a 9 mm bullet from .38 caliber gun?

The calibers refer to the diameter of the bullet. A 9 mm bullet has a diameter of 9 millimeters, while a .38 caliber bullet has a diameter of .38 inches, which is approximately 9.65 millimeters.

Since 9 mm cartridges are smaller than .38 caliber cartridges, a 9 mm bullet would be too small for a .38 caliber gun barrel, leading to unsafe firing circumstances.