New shot spotter at the range - ballistics calculation

[Left to Lobster]

My range installed indoor shooting tubes this year. They use a system to “triangulate” sound via speakers at the target. It’s a beautiful setup. It will spit out your FPS at the target. What’s the equation mathematically to calculate muzzle velocity with say velocity at 200 yards?

 

[smoothy8500]

Yes, E targets are very nice. Along with the average velocity at targets it gives the SD of those numbers. I wonder how much the SD at distance relates/matches the muzzle SD?

 

[Rio Precision Gunworks]

Yes, E targets are very nice. Along with the average velocity at targets it gives the SD of those numbers. I wonder how much the SD at distance relates/matches the muzzle SD?

Depends on the distance. At relatively close ranges, muzzle velocity and down range velocity will be pretty close.

Once distances is far enough for drag to start mattering, you'll start seeing MV and DV move further apart. It won't be perfectly linear, but it will follow the SD of the drag of the projectile used. The more consistent drag is from bullet to bullet, the closer the DV velocity with be to the MV.


It's basically along the same lines as you should almost always be seeing a circular shot group pattern at short range (provided you shoot enough shots for the random circular dispersion to materialize) and if not, something is wrong. But at distance getting an oval shaped group with longer vertical than horizontal is perfectly normal due to the SD in drag.

Its also the reason why something like an Oehlar 89 uses time of flight from rifle to target to calculate BC.