Are 380 caliber and 38 caliber the same?

You'd think they would be--right?

Depending on the tolerances of a particular weapon, you might be able to use SIMILAR projectiles.

A .380 caliber is actually has a .355 caliber projectile--so does a 9mm.

The typical .38, as in 38 Special is .357 caliber.

So, when all is said and done, .355 caliber is smaller than .357 caliber. No, they are not the same, but close.