I lucked into a two-week trial of the new doppler chronograph from Garmin. It seemed to me to be the gun writer’s work-saver. Properly set up, it appeared, one could shoot the usual multiple five-shot groups onto the target, effortlessly capturing the velocity data all along.
This device arrived in the midst of a late Fall monsoon, the first rain we’d had in a while. I wasn’t going to take the family ride down into the bottoms in squall – even if Garmin says the Xero C1 is certified water resistant, I’m less so.
It was a few days, on our last day of publication before the holiday, that I got to sneak out to the range between pre-holiday errands. A short trip, I had a point-and-shoot camera, the cell phone, ear and eye pro, the “smaller than a deck of cards” Garmin, a S&W M351PD 22 Magnum snub and two varieties of the CCI Maxi-Mag 40 grain 22 Mag. ammo. One was the “milk carton”-style bulk pack and the other was more-premium packed fifty to the plastic box.
Set up was easy enough I messed it up. When the chrono shows a confirmation screen, you don’t start shooting. Press the “okay” button, then start shooting.
Shooting the 40 grain JHP “bulk pack” first, I got an average of 980 fps on the little chrono. It was interesting to see it go from the high reading, 1,007 fps down to 959 fps before rebounding up the last couple of rounds.
The ‘premium’ packed MaxiMag, likewise a 40-grain JHP, was marked 1,875 fps on the box. This is probably from a rifle. From this little heater, the average was 1,033 fps – a considerable increase. In this five-shot exercise, it started at the low point, 1,008 fps and wandered between high-and-low through the five-shot string.
Back in 2020, I shot the same ammo, from a fifty-count box, out of the same gun. The average velocity from the conventional chronograph for CCI Maxi-Mag 40gr JHP was 1,073 fps. As the temperature was a little higher last week – and other variables doubtless intruded – the 1,033 fps average wasn’t that far off.
As to the little gun fired on the inaugural outing of the ‘chronograph of the future,’ the Model 351PD, chambered in 22 Magnum rimfire, is a seven-shot, 11.2-ounce revolver with a stainless-steel barrel mounted in an aluminum barrel shroud. The frame and cylinder are likewise fabricated from aluminum. The gun has an external and accessible hammer – unlike its sibling the 351C, a Centennial-type revolver. The 351PD has a U-notch trough in the frame for the rear sight. The front sight is the HI-VIZ Fiber Optic with an orange tube. The stocks, originally some visually appealing wood, are now changed out for Crimson Trace Laser Grips (LG-350), and the gun measures a mere 6.2 inches with its sub-2” barrel.
I changed the stocks more for assistance with my hold than the laser aiming aspect. I proved that by shooting the annual LEOSA revolver evolution with the eleven-ounce revolver, fighting the heavy DA trigger.
With the old chronograph in early testing on 22 Mag handgun ammo, I found that the heavy-bullet Hornady Critical Defense yielded just under 1,000 fps, while Speer Gold Dot was hotter at around 1,250 fps with a bullet a scant five grains lighter. I look forward to trying this ammo – as well as other guns and loads – with the Garmin before it has to go back.
The Xero C1 data on these loads from this gun follows:
Session Note M351pd CCI 22 Mag MaxiMag 50 pack
# SPEED (FPS) Δ AVG (FPS) Kinetic Energy (FT-LB)
1 1008.3 -25.2 90.3
2 1036.2 2.8 95.4
3 1056.2 22.7 99.1
4 1024.7 -8.7 93.2
5 1041.8 8.4 96.4
-
AVERAGE: 1033.4
STD DEV: 16.1
SPREAD: 47.9
Session Note M351PD, CCI bulk MaxiMag
# SPEED (FPS) Δ AVG (FPS) Kinetic Energy (FT-LB)
1 1007.2 26.9 90.1
2 994.3 14 87.8
3 969.3 -10.9 83.4
4 959.3 -20.9 81.7
5 971.1 -9.1 83.7
-
AVERAGE: 980.2
STD DEV: 17.7
SPREAD: 47.8
— Rich Grassi