With all the issues with the Magneto Speed and LabRadar I am not sure why the Oehler Research chronographs aren't at the top of the heap. They are the original, very accurate and never have a problem with harmonics or picking up a bullet. I've been using mine since 1982 and have piles of notebooks filled with reloading data and all loads are chrono'd with ES, SD's and Velocities plus group size, which are necessary for proper load development. I wouldn't consider strapping something to my barrel during load development thats going to affect harmonics/groups. If they are good enough for the military/US Gov agencies they are good enough for me.