well then how about the "30 39" thats short,after all it is about the same as a 30 30.
The 30-30 was so call because it was a 30 caliber bullet over 30 grains of powder. Back in the day names made sense. Just like the 7.62x39mm makes sense. a 7.62mm bulet loaded in a 39mm long case. That way you don't confuse it with the 7.62x51mm, 7.62x54Rmm, the 7.62x63mm or the 7.62x51R.