Notes :

	Ballistic Coefficient Note

	The BC values given are good averages at 'Normal Temperature and Pressure' 
	and at sub-sonic velocities. The value can vary between different barrels 
	(up to +/- 10%), in the same batch (up to +/- 5%) or with environmental conditions. 
	BC increases by about 3% per 1000 Feet, and by about 0.3% per C° (around 0.2% per F°).
	Depending on the pellet design, the BC may also vary slightly with velocity.  

	Calculating Ballistic Coefficient:

	Ballistic Coefficient is derived from the observed velocities at two ranges.

	BC = (R1 - R0) / (Loge(V0 / V1) * 8000)

	where:

	BC = Ballistic Coefficient
	R0 = Nearest Range (Yard)
	R1 = Furthest Range (Yard)
	V0 = Velocity at R0 (Ft/s)
	V1 = Velocity at R1 (Ft/s)

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	Pellet Weight Note

	Pellet weights can vary by up to +/- 4% in the same batch for quality pellets;
	perhaps a little more for cheaper/nastier ones.

	Calculating Kinetic Energy:

	E = M * V2 / 450240

	where :

	E = Kinetic Energy (Ft-Lbf)
	M = Pellet Weight (Grain)
	V = Velocity (Ft/s)

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	Velocity Coefficient Note

	The Velocity Coefficient (VC) column was added on 10th February 2008
	as an alternative to Ballistic Coefficient. VC is simply an alternative measure 
	of ability of the pellet to overcome drag (i.e., aerodynamic efficiency) and 
	represents the deterioration in velocity (Ft/s) for each Yard traveled.

	i.e.,

	VC = 1 / Exp(1 / (8000 * BC))

	where:

	VC = Velocity Coefficient and
	BC = Ballistic Coefficient

	For example:

	0.22 JSB Exact: BC~0.031 so VC = 1 / Exp(1 / (8000 * 0.031)) = 0.99598
	
	If MV = 800 Ft/s then V1 = velocity @ 10 Yards = 800 * (0.99598)10 = 768 Ft/s

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 	Wind-Drift Note

Simply . . .

D = W * sin(A) * (T - (R/MV))

Where :

D = Wind Deflection (Feet)
W = Wind Velocity (Feet/second)
A = Angle between Wind Velocity vector and the trajectory
T = Actual transit time between muzzle and target (second)
MV = Muzzle Velocity (Feet/second)
R = Distance between muzzle and target (Feet)

Note that the term R/MV is the transit time (between muzzle and target) in a vacuum and that, 
for a wind vector at 90 degrees to the trajectory (the worst case), sin(90 degrees) = 1

We also know that:

T = 24000 * BC * (Exp(R / (24000 * BC)) - 1) / MV

Where:

T = Actual transit time between muzzle and target (second)
MV = Muzzle Velocity (Feet/second)
R = Distance between muzzle and target (Feet)
BC = Ballistic Coefficient

So, it is clear that the wind-drift (D) at any particular values of A, MV and W depends 
only on the Ballistic Coefficient of the projectile.

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	Velocity Retention Factor Note

	The Velocity Retention Factor (VRF) is yet another (somewhat arbitrary) measure
	of aerodynamic efficiency used by some ballistic modeling software. VRF is similar to VC
	but without the implicit accuracy. It is defined as the ratio of the velocity at 10 Yards
	and the Muzzle velocity. 

	i.e.,

	VRF = V1 / MV

	where:

	VRF = Velocity Retention Factor
	MV = Muzzle Velocity and
	V1 = Velocity measured at 10 Yards from Muzzle	

	In terms of the (more useful) VRC value:

	VRF = (VRC)10

	Why 10 Yards? I've no idea. It's certainly not a great choice - much too short given the 
	accuracy and repeatability of commercially available chronographs ... but what do I know?
	VRF data does not have the same general applicability or utility as BC or VRC and is included 
	here only for the sake of completeness and for software that specifically requires it.

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