I bought a ProChrono last year on John Barsness' recommendation. It sits midway between the skyscreens of my Oehler 33. This way, I get two readings from two chronographs for every shot. The ProChrono has never failed to record a velocity, and it always agrees with the expensive Oehler. I must admit that if I only had the ProChrono--without the Oehler--I'd still be a happy lad.
If you don't have a chrono, buy this one from Tetralaw and have your spouse give it to you for Christmas.
"For every complex problem there is an answer that is clear, simple.....and wrong." H. L. Mencken