I got the idea from Greg at primal rights youtube video when he put his garmin 50 yards down range.
I noticed my 223 wasn't setting off tannerite at 300 yards reliably so I wanted to get some actual velocity data.
According to my ballistic software, my load still had an impact velocity of 2,500 fps (minimum required to set off tannerite).
I am running the 53 grain vmax in my 12 twist factory remington, when you put this into a stability factor calculator, it is right on the edge of being able to stabilize (Sg of 1.0).
I thought this was the source of my issues, my velocity being lower than I expected because of the bc degradation due to the stability being poor.
So I decided to stick my garmin 302 yards downrange on my tripod and check the numbers vs my sig bdx software. My rifle shoots 1/2 moa very consistently so I wasn't worried about potentially hitting the unit.
I placed the target 13 yards past the garmin downrange at 315 yards to give the doppler some room for the signal.
I took 3 shots, went down to the unit, and had 3 shots registered. Not a single hiccup.
To my surprise, the unit matched up perfectly with my ballistic software. Very nice that this unit gives me the ability to confirm numbers downrange so easily.
This garmin unit has yet to disappoint!!!!!