Chronograph not working….

[tproehl]

Just get the new Garmin C1 Pro

[Tommy Laing]

My new 33 year old ProChrony crapped out last month too. Same thing, display is gone. Someone has the new display on eBay but I couldn\’t figure out how to get in the old unit. I did find a used unit for $50 so I purchased that and I\’m back in business.
Now I\’m looking for the chorded remote so I don\’t have to get up and go look at it for every shot. The Bluetooth would be nice too but my pocket book wasn\’t that ambitious.

[flyingbrass]

My ProChrono is around 10 years old and still worked fine when I dug it out a few months ago, though I\’ve not used it much in recent years. A few years ago I got sloppy and bent one of the screen rods with a .45 ACP bullet. I was too focused on reading the numbers from each shot and got too lazy when essentially point shooting the rounds through. Don\’t do that.

I bought the extra bluetooth module soon after it came out (I think it cost $50ish back then). I used it for a little while but don\’t bother with it any more. I don\’t know about the newer versions with built in bluetooth, but what I have doesn\’t offer any control from the user end. I can\’t remotely change shot strings, etc. That would be a real pain at a shooting range where I would have to wait until a ceasefire to walk out to deal with the chrono. I\’ve not used mine at a range because of this. Fortunately, little of my shooting is done at a range. The radar chronos have a big advantage in that situation.

Years ago my shooting buddy bought a LabRadar, which IMO was a PITA in many ways and not worth the money. It had problems from new picking up shots, and he had a bad experience dealing with their customer service. Recently we have been using a Garmin Xero, which is more of what a modern chrono should be. I have a few nitpicks about the Garmin, but overall, it\’s wonderful and practically magical to someone who has dealt with optical and cranky LabRadars over the years. I wouldn\’t buy an older style LabRadar today even if dirt cheap. Nor would I buy their newer model even if it\’s decent due to previous poor customer service experience.

If I was going to buy a new optical chrono today I\’d lean heavily toward another ProChrono because mine has been impressive for the price. Years ago I encountered an odd situation that provided some interesting information.

I had been shooting through my ProChrono from the bed of a pickup. I moved the chrono, still on its tripod, several feet to the side when my friend shot his rifle. I noticed the ProChono was registering his shots and velocities. Bullets were not passing through the chrono. It picked up the shockwaves.

Paste from an e-mail I sent to him about the results:
——
The chrono was registering about 1180 FPS during your shots. It was picking up the shockwaves at the speed of sound.

Sound speed at different temps:

80 degrees: 1139 FPS
100 degrees: 1160 FPS
120 degrees: 1180 FPS

The air temperature wasn\’t 120, probably more like 85. The readings are slightly off because the chrono wasn\’t perfectly lined up with the origin of the sound. It was rotated a little, reducing the distance between the sensors, which caused the velocity readings to be calculated higher than actual.

Similar happens with bullets, which is why it is important to keep the chrono lined up so bullets travel parallel with the top of the chrono.

Since the speed of sound is constant at a given temperature, this was a good measure of the chronograph\’s precision. 12 shots were recorded.

high: 1192
low: 1180
avg: 1186
es: 12
sd: 4

Specs for the ProChrono say accuracy is \”+/-1% of measured velocity, or better.\” I can\’t vouch for accuracy, but precision was better, at least this time for a single string of 12 \”shots\”. The ES of 12 is a total variation of 1.01% (+/-.505%).

If the error is linear, which it may be, 1.01% would be an extreme spread of 27.3 FPS at 2700 FPS.

Based on the collected data, that\’s what the chrono would show if you could fire shots all going at the same exact speed. It\’s not capable of measuring super tight extreme spreads. Sure, it will occasionally report some low extreme spreads in strings of small sample size, but they don\’t mean anything. It\’s akin to reading ten-thousandths on calipers only precise to .001\”.
——

Radar chronos, even super high end ones costing tens of thousands of dollars, can have some precision and accuracy issues also. I\’ve had odd average velocity readings from the LabRadar with small base .223 bullets that shouldn\’t have been so different and didn\’t match what happened on paper at long range to the extent that I don\’t trust the readings. For $150ish I think the ProChrono is quite good, and if properly used (shooting straight through) you aren\’t losing much if anything that is of practical use as far as results are concerned compared to the consumer radar units costing much more. Opticals are much less convenient to set up and use, particularly when shooting rifle prone and have to get everything aligned just right. Not much of a problem for handguns. Radar, when it works well like the Garmin Xero has so far, is much less hassle.

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