I owned three Shooting Chronys from the early 1990s until around 2008. The first I tested against an older, very reliable chronograph, one of the primitive models that required turning a dial around a series of numbers. Some would light up, and you could then look up the velocity in a booklet.
Bought that first Chrony because it would be a lot faster at the range, and easier to set up. I checked it with some .22 Long Rifle ammo, and the Chrony got the same velocities. Used it for a few years until it quit working at all, perhaps due to so many shots being fires from higher-powered rifles. Bought it so cheaply (as I recall $50) that it wasn't worth repairing, so I bought another. That one showed increasing velociities over a few years--so slowly I didn't realize it was happening until it became too obvious. Sent it back to Chrony, and when it came back did the same thing. Junked it and bought another, though should have learned my lesson by then, because I needed a chronograph right away due to my work.
In the meantime Oehler started making 35Ps again, so I ordered one. That particular Chrony did NOT match the velocities of the Oehler, and velocities also varied far more under different light conditions. In the meantime I'd run into more than one guy at the local range who had problems with his Chrony, including one who's Chrony starting showing velocities 500 fps faster than normal with 180-grain .30-06 loads.
At that point I started trying other chronographs as well, including a ProChrono Pal, which I used for quick range trips because it was quicker to set up than the Oehler. When the Pal showed up I tested it against the Oehler during a long afternoon range session lasting about 4 hours, and with several rifles the readings were right together, including under different light conditions.
That said, the Pal was not nearly as good for real ballistic analysis, because the light-screens are so close together, but it worked fine for quick sessions until an unexpected gust of wind toppled its tripod one day. Sent it to the factory to be repaired (which worked, unlike my Chrony repair), and in the meantime ordered another for backup. Tested it against the Oehler too, and it was also dead on. Eventually gave one of them to a younger friend with a growing family who really couldn't justify even $100 for one. It's still working great for him.
After that purchased several other chronographs, primarily to test for magazine articles, including a couple of Magnetospeeds and a LabRadar. All of them recorded the same basic velocities the the same loads. Have seen so many Shooting Chronys NOT do that I've lost count.
Might also comment that if you haven't used your Chrony in several years, you don't use a chronograph much.
