I have an Alpha Chrony about ten years old or so. I have been suspicious of its accuracy because my loads never chronograph at the speeds those books claim. Seems like most of my rifles are about 200 fps slow. My shooting partner has a newer Beta Master Chrony which he had never used. Last range trip I set them both up in line. The Beta Master has a remote readout so I set it in front of mine which you read off the front of the unit. I put a brand new battery in his but it only lasted a couple shots. I don't know if the battery was bad or if his Chrony is bad. It would work a couple shots at a time then I had to turn it off and let the battery recover and then it would read another couple rounds. In spite of that I got a few simultaneous readings.
The interesting thing is that the Chronys read closer to each other with larger bullets. My neighbors on the firing line were verifying their zeroes for hunting and had several rifles they wanted to clock. We fired a 264 Win Mag, 270, 7mm Rem Mag, 30-06 and 338 Win Mag over the two Chronys. The 264 is mine and I got two readings with both Chronys. The readings are 20 FPS and 21 FPS slower with the Beta. Unfortunately I didn't write down the readings from the other fellows rifles but the 7mm had less difference than the 264, the 30 caliber was better yet at about 5 FPS difference and the 338 was only 2 FPS slower on the Beta. This stands to reason because the Chronys sense the bullets shadow and bigger bullets cast bigger shadows.
If we get the Beta working I think I will try clocking some 22's up through 35 caliber to see if the trend holds up. Of course the other thing is that my Chrony is probably fairly accurate which means those dang reloading manuals lie!