Originally Posted by
RobS
I normally slug the barrel throat first by placing a pure lead slug nearly the barrel diameter (in your situation .480"ish would work) into the forcing cone/barrel and then I place the barrel muzzle on a folded up towel on a study table. Then I find something to push the slug into the barrel throat. Typically I use a tapped up the handle of a crescent wrench to keep metal on metal contact from happening and put it through the frame perpendicular to the barrel to push the slug downward into the throat/bore. Simply use a wooden dowel to push the slug back out and measure. I then run a slug the full length of the barrel as well to check the entire bore's diameter and to see if there are any notable constrictions in the barrel. Make sure to oil the barrel and the slug before you make a go at things. Once you slug the barrel if this will go through the cylinder throats (clean and all 6 of them) then you know the cylinder throats are large enough.