Measuring it exactly on a finished gun would be difficult enough that I'm not sure I'd waste my time, especially since the difference is so easy to see and feel.

It strikes me that perhaps the best way is determine how breech heavy the barrels and fore-end are as a unit, and how action heavy the action and butt-stock are as a unit. An action size that is correct for caliber permits thicker chamber walls and greater barrel contour downtube, thus concentrating more weight over the action, which also makes it easier to balance well. DRs built on grossly undersize actions (Merkel, Krieghoff, etc) must have thinner chamber walls to fit the action and, consequently, can't have much barrel contour if the target weight is to be achieved. This puts a materially greater percentage of barrel weight forward, and less between the hands. Combined with the small action, this also often means that weight must be added to the butt (ala Merkel) in order to achieve balance, making the linear weight distribution even worse.

Comparing the two types, side by side, the difference is visually graphic. The difference in handling and feel is equally graphic.