Yes, you would want the distance that the bullet base travels but for the shockwave, I assume you'd want the full distance to the breech.
I wasn't sure if your numbers were a round trip or one way.
If it's round trip,you'd want whole numbers, if it's one way you'd want even numbers, not the .5s I mentioned.
Chris Long has an excel version of the calculator here:
Still happily answering to the call-sign Peetza.
The problem, as you so eloquently put it, is choice.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.