At what distance do you measure the velocity at?
at the muzzle or 10yrds?
most of the time there is only fps listed and not the distance it's measured at?
Anyone ever use a high end radar to measure like Labradar?
Most people relate it back to the muzzle because thats the one undeniable constant. Opticals are forced to measure further out from the muzzle a good ways but people always relate it back to the muzzle for any external ballistics calculations.
Labradar measures the bullets time over a number of distances and then calculates what it would have had to start with at the muzzle and provides that as the big number displayed (you can view all of the individual data points on the sd card). So similar to the old opticals that measure out from the muzzle but instead of just you manually adding say 10 fps ball park estimate to enter into a calculator it maths you an "actual" muzzle number.
Magneato speed is really the only one that measures "at the muzzle".
Edit: I see in another thread you commented you just bought a labradar. I love mine.
If you are shooting with a bare muzzle or a muzzle break you will be getting enough blast to reliably trigger the radar so you will want it to not be in the direct line of boom just to avoid beating on it.
If you are shooting a silencer you will want to try and arrange it as close as you can and in the line of blast so that it has enough ooomph for the recoil sensor to trip and read the measurements.
Its pretty intuitive to position for me at least once Im using it.
If you are shooting 22lr and having issues switch it to pistol mode to look for the low velocities. In rifle mode it will be looking for something faster so it may ignore the slow things.
As spife stated any ballistic calculations expect muzzle velocity. Some calculators such as JBM even have a field to list the distance to the chronograph. You can see it in the second section here:
