I'm hoping someone can walk me through this. What is the calculation I would have to make in order to calculate the amount of freebore that I want to have in my finished rifle?

Essentially what am I going to ask my gunsmith to do.

Here is what I want in words.

I want to end up with a .308 that when 180gr and 165gr bullets are loaded to the lands, the bullets will fit in the magazine. That would be for most bullets not all.

Does anyone know the equation for this calculation so I can ensure there is no miscommunication between the smith and me.

Thanks

Tom