Estimating Shell Weights from Existing Designs(Created 2 July 2016)

Webmaster's Note: This formula was originally given to me by a friend on 23 October 2007. It took until now (2 July 2016) to actually get around to cleaning it up and testing it.
This formula works for both projectiles and propellant masses.
Mass_{Scaled }= (Caliber_{Scaled} / Caliber_{Reference} )^{3} * Mass_{Reference}
Where:
Mass_{Scaled}
= Mass of the scaled shell.
Mass_{Reference}
= Mass of the reference shell.
Caliber_{Scaled}
= Caliber of the scaled shell (in inches or mm)
Caliber_{Re}_{ference}
= Caliber of the reference shell (in inches or mm)
EXAMPLE 1: How heavy would a hypothetical 155mm HVAP projectile be, if we used the weight of the existing 90mm T30E16 HVAP shell (16.7 lb)? (155 / 90)^{3} * 16.7 = 85.3 Thus, a 155mm HVAP projectile would weigh 85 pounds. EXAMPLE 2: How heavy would a hypothetical 76mm HVAP projectile be, if we used the weight of the existing 90mm T30E16 HVAP shell (16.7 lb)? (76 / 90)^{3} * 16.7 = 10.05 Thus, a 76mm HVAP projectile would weigh 10.05 pounds. (The actual 76mm T4 HVAP round weighed 9.5 pounds, so this scaling method turned out to be off by about 5%, so keep that in mind for evaluation purposes.) 
M_{Shell} = 0.442 * D_{Shell}^{3.054}
Where:
M_{Shell}
is Shell Weight in pounds.
D_{Shell}
is Shell Diameter in inches.
EXAMPLE: How heavy would a hypothetical 31.5” nonsuperheavy shell be? 0.442 * 31.5^{3.054} = 16,664 Thus, a 31.5” Shell would weigh 16,664 pounds (the 80 cm Dora Shell of the same calibre weighed 15,652 lbs) 