Prochrono

I assume you are asking about the ProChrono... I have one and it works great on my 30cal, however it has to be just PERFECTLY placed to pick up my 0.177. I ordered one of these after seeing one at my club match.

http://www.edgunwest.com/store/p6/Edgun_Mini_Chronograph.html

Honestly I would have gotten Edgun instead of the ProChrono if it had been available when I ordered my ProChrono. The ProChrono means dragging it (4x6x14 box) plus a tripod to mount it. I have to pay close attention to lighting conditions and the little diffuser that come with those are a joke, unless the light is directly overhead they don't do anything. The Edgun is tiny in comparison, can be slipped into a pocket on a gun case, I worry a bit about fit on the barrels I have, but otherwise...