denton,
I have owned two Shooting Chronys which declined in accuracy over time--and also have a local friend who had the same thing happen. They did not just quit working. Instead two started showing velocities that were obviously much higher than they should have, and changing batteries didn't help. The third started showing variation between sunny and cloudy readings of 100-150 fps. Sent that one back to get fixed, and it worked OK for a while, but I was starting to mistrust them.
Back then I was doing a LOT of shooting with a wide variety of cartridges, and eventually concluded the muzzle blast of some of the bigger rounds was shaking something loose. That's when I acquired my first ProChrono, and those problems ceased. (Purchased another PC maybe two years later, in large part to see if it worked as well, and also tested it against my Oehler 35P while shooting a wide variety of cartridges from .17 to .416 caliber. The second one worked just as well, despite me using the plain old overhead filters, instead of the furnace filters that Al Nyhus has used to good effect.
But the first also just kept trucking, so I gave the second one to a young friend with a growing family. This was several years ago, and he's still using it, with cartridges as large as the 33 Nosler--with the chronograph less than five feet from the muzzle.
John
