Volleyfire, following is a short explanation of handling.
Stock dimensions fit the gun to the shooters physique. Handling fits it to his strength, muscle speed, hand placement preference, and shooting style. As we use differing stock dimensions for differing shooting situations, so do we use differing handling. The objective of any fit is to better adapt the gun to the individual shooter. Better fit may result in higher scores and/or more fun.
Weight, balance, unmounted and mounted swings are the four dimensions of handling. Swing is the dimension that tells us the effort needed and/or time required to point the gun in a differing direction. Moment of inertia is the measurement that tells us swing effort. MOI at balance point is for unmounted swing effort and MOI at butt is for mounted.
MOI measures the resistance of an object to changing rotational velocity. The gun resists starting swinging proportional to its MOI. It resists stopping swinging likewise. Increasing MOI indicates increasing effort to start swing and stop swing.
Following are three examples of averages:
Average 2"-12 Bore Game Gun weight = 5.37#, balance = 3 5/8 " to trigger, unmounted swing = 0.95, mounted swing = 4.75, gauge = 12-2", avg bbl length = 26, avg LOP = 14 1/2"
Average Game Gun 6.50#, 4 1/2", 1.45, 6.38, 12-2 1/2", 28, 14 1/4
Average Light Pigeon/High Pheasant 7.21#, 4 5/8", 1.67, 7.46, 12-2 3/4", 29", 14 3/4"
MOI at balance is measured on a constant torque turn-table driven by a bob-weight. The gun is clamped in a vise atop the turn-table. One revolution is timed and MOI calculated via an engineering formula. MOI at butt can then be calculated via the parallel axis theorem.
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