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New Chrony F1 erratic readings


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Just took my new Chrony F1 to the range today to test different loads in my 9mm and 40 cal. USPSA guns....

My problem is that my readings varied a lot....I started with my 9mm loads, using N320, Montana Gold JHP's and minimum crimp....on a Dillon 550B

I would get a 927.3 reading, and then a 1,057.0 reading, then a 884,6 reading....

I measured 10 feet from the table I was shooting at to the Chrony sitting on another table....

I marked the rods 6 inches up from the sensors..

The weather was cloudy and 52 degrees, with a little wind...

I don't get it...why are the readings so far apart?

Does it matter if some shots are a little lower to the sensors than others?..would that register differently than a higher shot?...I would not think so, but ???

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Being closer to the sensors - as long as they weren't hit - would not have any appreciable effect on the velocity.

If a friend has a chronograph you could check them against each other.

If it is cloudy, shifting intensity of the available illumination could be a cause of the varying velocity. If possible, try on another day and see how it works then.

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Thanks guys...

I had a brand new battery in the Chrony and yesterday was the first time I tried it...

I am hoping that it isn't my loads, since the N320 meters really well, and my 550B is only 15 months old

I will try it again on a different day and try some factory ammo to see if it does the same thing...and I will try another new battery

Anyone else out there with the same problem?

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Leave the diffusers on and put a target over the diffusers. Try that.

+1 Leave the diffusers always. I put some velcro on top of them and velcro a no shoot over the top on bright sunny days

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Don't use the target, I always use the diffusers. However, since I always use them I can't really say what would happen without them. On a solidly cloudy day I can't see that it would make any difference, on a day where the sun is in and out I'd use them.

This assumes that the sun is overhead, it it is at an angle then the sunlight probably hits the sensors directly.

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Depending upon your altitude, you could be at the speed of sound which causes bad readings as the chronograph reads the Bow Wave differently than the bullet itself. you may want to check out some slightly faster loads to see if thats the problem. A soluiton is not yet here, but check out www.mylabradar.com , its not sensative to light or subsonic bullets.

Good luck.

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I had a very similar problem the other day. I went out with my match 223 ammo and wanted to chrony it for my ballistic app.

The strings were either closely grouped around 3,000 fps or closely grouped around 2650 fps. It was really odd, it was one of the other, nothing in between.

I was pretty sure it was the chrony since the groups on paper were great.

Could be a dying battery, could be something else. It was cloudy that day as I recall. The chrony was an alpha shooting chrony

Edited by Onagoth
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Leave the diffusers on and put a target over the diffusers. Try that.

I like this idea. I noticed I would have varying results with my F1, if the sensors were not covered by the diffusers. So the extra coverage may be just what you need.

Sent from my iPad using Tapatalk

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  • 2 weeks later...

I went out with my Chrony and did everything you guys recommended...new battery, a no-shoot target velcroed to the diffusers, and shot at 12 feet instead of 10 feet...

Nothing seemed to work...my first shot had an error code, my next shot registered, then my 3rd shot did not read at all..

I gave up and took it back to Cabellas, who gave me a refund, and then an hour later I got on Amazon and ordered a CED ProChrono....hope it works better

Thanks guys

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my issue didn't go away either. I tried with some handgun loads on a cloudy day from about 10 feet. half the shots registered velocities that I expected and the other half were like 200 fps.

I think the chrony is done. Well beyond warranty period though

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