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## Shotgun Ballistic Calculator

Started by gvp, December 21, 2020, 01:15:46 AM

#### gvp

I've made a very simple excel file in order to calculate Velocity, Energy and TOF for shotgun BB's.
1. What is the BB's ballistic coefficient ? Can it be calculated ?
2. Any idea how to make this simple excel file more reliable according to atmospheric conditions and the subsonic, transonic and supersonic region ?

Thank you in advance,
Bill

#### admin

#1
I couldn't resist googling. Since 2008 some scientific papers were produced on the matter. https://www.sciencedirect.com/science/article/pii/S2214914717301459 has an interesting one which I quickly scanned
you can use it to check your table.
Next posts on the bc calculation

#### admin

#2
I have (re)done the research.

The ballistic coefficient is computed from m/(d*d) where m is the mass of the pellet in lb and d its diameter in inch

or bc = density*pi*d/6

density lead = 0.41 lb/in^3
density steel = between 0.280 and 0.291 lb/in^3
The drag function to use is "GS" in bfx which matches the one in the above link

#### admin

e.g.  .50 round lead ball bc= 0.107 lb/in^2

#### admin

#4
by the way,
bfx looses accuracy for elevations above 15 degrees. In practice this affects max range / long distance calculations.