Puddle,
Good technique! Did the same basic thing for many years before computer ballistic programs and laser rangefinders.
I still confirm velocity/computer results at the local range early in the mornings when the air is still.
The range has a pile of gongs scattered across it out to 1000 yards, and sometimes I shoot that far, especially when testing a magic dialing scope. But for my own purposes usually quit somewhere from 300-600, depending on the rifle.
