Some time this coming week I will have to part company with the chronograph that I’ve used since 1985. It’s called a Pro Tach, and was made, I believe, by a company called Competition Electronics, which is still very much in business and making chronographs, albeit far more advanced ones.

The Pro Tach was simplicity itself. It ran on a 9V battery, had an on/off switch, and when you shot over its two sensing gates it told you how fast the bullet was going. That was all it did. It would not give you the weather, or the mean velocity variation between shots, or the number of votes by which Hillary Clinton will carry New York State in 2016.

It got rained on, snowed on, tossed in the back of my SUV countless times, and on a couple of occasions had sand thrown into it by bullet impact. It was not perfect. It relied on cardboard aiming guides that you had to insert in slots in the top of the case, and if the sun was out you had to fit plastic shades onto the top of the aiming guides. If a gust of wind came along the shades blew off, and sometimes the guides blew off. If you were not careful to place the chronograph at least a dozen feet from the muzzle, the blast would blow off the aiming guides.

Sometimes you would get a weird reading for no apparent reason, and aligning the tripod and the chronograph with the muzzle of the rifle and the backstop was always good for a few minutes of merriment. But it worked. It worked well enough to last for 28 years and rack up enough velocity data to fill up two stenographer’s notepads, writing on both sides of the page.

But the aiming guides are so frayed that they won’t fit into their slots, and the plastic shades are cracked and splintered beyond use, so I’m getting a much more advanced instrument which has none of these inconveniences.

I don’t know what I’ll do with the Pro Tach, but it will be done with real sorrow and a sense of loss. I’ve traded in SUVs that have served me faithfully for years and many thousands of miles and have been unable to look at them for the last time on the dealer’s lot. If you use something long enough and hard enough, and it serves you well and faithfully, it becomes more than a machine. And saying good-bye is a hard job indeed.