Odd chrono results

[Wvaughn7]

I bought a new Caldwell ballistic chronograph this past week to work up major loads for the upcoming USPSA season and finally got to the range yesterday to try it out. We started out running a couple different rifles through it to see if the chrono was reading where we expected it to and it did. I then ran my major loads through a Glock 17 with Lone Wolf threaded barrel and all seemed normal there as well. The oddity came when I ran my minor loads out of my Rock Island 2011 9mm. I was shooting Xtreme played 147 bullets over 3.5 grains of Bullseye as an OAL of 1.160-1.165. I shot three strings of ten through the chrono and came up with an average MV of 1260, ES of 11fps and SD of 3.2 fps. This is a power factor of 180. Is there a way the chrono just isn't working correctly with this one load, or is everything wrong? What could be the cause? I appreciate any help you all can give.

[brytec]

We are exactly in the same boat ... I have the Caldwell as well ...chrono last Thursday and it was very inaccurate .. One of the guys I shoot with was at the range with his own subsonic chrono and we compared and shot together.. The results were more consistent in his chrono... I'm returning this to Amazon get my $75 back...You really get what you pay for with this one!!!

Do you have the complete kit with lighting because from past experience these are very light sensitive for some reasons!!!

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[Wvaughn7]

I do not have the light kit, but it was a bright sunny day outside. I did have the shade screens in use and no reflective surfaces around except for the bullet. It's odd to me that only one load was showing up so fast with the rest being pretty consistent. I didn't have problems with errors or inconsistent readings, just that they all seemed high with this bullet. Could it be a bullet issue?

[Steve RA]

Yes, try the same load with a different bullet and see if that is the problem.

[Hi-Power Jack]

I've never had results like that with my Chrony ($75).

[MemphisMechanic]

ProChrono. Not that much more $$$ and it just works and works and works outdoors or indoors (if you aim an incandescent light at the screens).

The Caldwell unit and the Shooting Chronys have never given me reliable results. Also... There's a separate subforum for chonographs and techniques - lots of reviews of various units there.

Edited April 18, 2016 by MemphisMechanic

[brytec]

I've never had results like that with my Chrony ($75).

Hey Jack were you using your Caldwell outdoors? Was it bright sunny day? Or does it have to be bright sunny day to get more accurate reading? Thanks

[Hi-Power Jack]

I don't have a Caldwell ... I have a Chrony.

I do get some spurious data, now and then, but it's usually a "flyer" -

I'll get 900 fps for 9 rounds and one round will get no result, or 400 fps.

So, I just disregard the spurious data.

[Wvaughn7]

The threads on the chronograph section seemed to paint a pretty good picture for the Caldwell which lead me to thinking it would be fine. I am going to give it another try on a cloudy day or with better protection from direct sunlight than just the diffusers. Maybe the light kit is in order to get it running correctly.

[rancher5]

Bright cloudy day help with accurate readings, Natural sunshade using natures overcast day, obviously without the rain.

[Postal Bob]

I have heard of others having erroneous readings, when using plated bullets.

As an example, I have the CED chronograph with the infrared light screens. Using it indoors I was getting consistent readings using my .40 limited gun. Similar velocities as when I was chrono'd at a match.

Then someone else shooting a .45 tried to chrono his loads. He was getting velocity readings ranging from about 800 fps to over 1600 fps. We know he wasn't getting that kind of velocity, for it would've blown the gun apart. But he was shooting Berry plated bullets. I don't know why, maybe because plated bullets are very reflective. But I have heard of other stories of erratic velocity readings with plated bullets.

Edited April 18, 2016 by Postal Bob

[N3WWN]

I wonder if the odd readings with plated bullets have anything to do with polished or shiny copper reflecting IR versus other finishes emitting or absorbing it.

Here's an article that mentions the issues with using an IR thermometer to measure the temperature of copper surfaces:

http://www.achrnews.com/articles/96272-noncontact-temperature-measurements-using-ir-thermometers

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[IDescribe]

The lighter and shinier the bullet, the worse the reading, and XTReme are oh so shiny. Color up the nose with a sharpy, and you should be fine.

Edited April 19, 2016 by IDescribe

[ChemistShooter]

I don't own a chrono and have never used one, but there's one in my future fairly soon so I've been researching them.

You might try painting the suspect bullets black with a Sharpie and seeing if that helps consistency.

[Wvaughn7]

Thanks for all of the recommendations everyone, I won't be able to make it to the range for a couple weeks, but I be sure to post back what I find to be the culprit. It may just be the shiny Xtreme's since the Acme coated seemed to be fairly accurate on velocity readings (high 1400's at 8.2 HS6 @1.140).