Both were Chrony's but different ages.[/quote]
Well, anything that happens must be possible. And now we have another example of one of the older Shooting Chronys going bananas. Hmmmm......
The fundamental system is extremely basic: A start pulse, a stop pulse, a count of the clock pulses in between, and a distance divided by measured time to get speed. Such a system either works right, or not at all. The only guess I can come up with is loss of hermetic seal on the oscillator unit, or some kind of internal contamination that slowly diffuses. I've never actually seen that happen.
So I am perplexed.[/quote]
Denton,
My first Shooting Chrony performed well, as far as I could confirm from shooting various loads (including the .22 rimfire used to test my first chronograph), and it was one of the early ones with cardboard "shades," as I mentioned previously purchased in the early 1990s.
Unfortunately it met its end around a decade later due to a misplaced .41 Magnum bullet. The two I had after that were the later models--which were the ones that declined in accuracy.
One of the things I learned from the Shooting Chrony folks during this period is that dust on the photo-sensors can cause problems, filtering in throgh the slots. Which is why I've placed transparent tape over the slots of every photo-electronic chronographs I've used since, including my Oehler. Tested that by, again, shooting the same ammo from the same rifle over the same chronograph. They all recorded the same velocities.
