Calculate Twist Rate, Bullet Length and Muzzel Velocity for optimum bullet stability
This algorithm and the constant 3.5 was suggested by Charlie Dell, in his book, "The Modern Schuetzen Rifle" and brought to my attention by "Tailhook" a member of the MSN BPCR discussion forum.
The constant "3.5" may be re-calculated to conform to known twist-length-velocity combinations that have been proven to produce bullet stability.
Define the Variables:
T = Twist rate in 1 turn per inches.
L = Bullet length in inches.
V = Muzzle Velocity
D = Diameter of the bore grooves in inches.
Constant = 3.5
Find the optimum twist rate from velocity, bore size and bullet length:
T= ( 3.5 * SqRt( V ) * D² ) ÷ L
Find the optimum bullet length from velocity, bore size and twist rate:
L = ( 3.5 * SqRt( V ) * D² ) ÷ T
Find the optimum muzzle velocity from bullet length, bore size and twist rate:
V = ( L * T ÷ D² ÷ 3.5 )²
Find a different constant to fit known optimim combinations.
Constant = L * T ÷ D² ÷ SqRt( V )
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Last revised: May 17, 2007.