There is no "proper" place to reference balance. Balance is useful for determining the % of the guns weight carried by each hand. Some shooters are quite sensitive to this division of weight and others are not.
Trigger (front) is the most convenient point to reference as it places the back/trigger hand. If distance from front hand to balance is measured, the weight distribution to the hands is the inverse of the center of the hand to balance point ratio.
Example: assume trigger hand center to trigger is 3 1/2", balance point to trigger is 4 1/2", and front hand center to balance point is 10". The total distance between hand centers is 18". 8"/18" = .4444 = 44.4% and 10"/18" = .5555 = 55.6%. Remembering the inverse relationship (the hand nearer the balance point carries a higher % of the weight), the trigger hand carries 55.6% of the weight and the front hand carries 44.4%.
You can reference any other point in the universe for balance and arrive at the same numbers, just a more complicated calculation. Breech face and hinge pin are the most often used. They came into use as the value of balance was not understood and some reference point was necessary to discuss balance in any form or fashion.
DDA
