Chronograph result differences

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Geezer-Jeff

Geezer-Jeff

Member
May 6, 2018
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Texas
I've done some fairly extensive testing of the Chrony Beta I bought about a year ago, but it was really finicky about setup, resulting in a lot of 'error' readings. I decided to buy a Caldwell G2 Precision Chrony to see if I got better results. I've certainly found it to be easier to set up and use, and I like the bluetooth to phone feature, BUT... I'm seeing a pretty consistent drop of about 6% in fps readings on the G2 compared to the Chrony. Shooting a Brocock Bantam, and the results are consistently lower across all power levels. I sure don't want to spend any more dollar$ for a tie-breaker. Anyone have any input as to which is 'probably' more accurate?
 
You have to figure maybe 2% accuracy, possibly less. But at the 2% that is plus or minus 10 fps if you were shooting at 500 fps. Personally I use a chrono to tune and to keep tract how my guns are shooting. If a particular gun was shooting 800 fps and later was at 750 fps I would be concerned there was a problem with the gun. I have the G2 also. Love it and don't really care if it's reading plus 2% or minus 2%. It's a comparative value that I am after. Personally I would stick with the g2 if I was in your shoes. But that's just my opinion. Happy Saint Patrick's Day evening
 
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I've got 4 velocity chronographs.

The Chrony F-1 and Chrony Alpha read 3 or 4% higher than the two Chinese chronographs.

I'm not sure which to believe but I usually use the Chrony Alpha which gives me the highest velocity readings. It might be a little optimistic, since at away matches when shooting over other chronographs, velocity usually reads a little lower.

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The Chronys are advertised as 99.5% accuracy or better. I assume that means +/- 0.5%.

The Caldwell is advertised as +/- 0.25%.

If true, you should see very little difference between the two.

Without some known, accurate baseline, I would not attempt to guess which is actually the most accurate.

If you check the SD between the two and it is close, than it is likely to be a calibration issue rather than a lack of precision.

If you need to tune to meet some velocity or FPE restriction, than the exact number can be important. But when using as a tuning tool to check for problems over time, or changes after modifications, either can work, just pick one and stick with it.


 
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+Thanks for the input, gents. I think I'm gonna have to shoot a lot more pellets through several guns before I want to lean one way or the other. At this point, the 6% -7-% difference I'm measuring seems excessive to me, but I'm pretty new to this, so... 

Scotchmo, the SD is a lot more than it ought to be, but as I'm doing all these measurements just for my own curiosity as to "what's goin' on", precision isn't going to affect me in any serious fashion. Down the road, I may have more input after trying different airguns. 

One question you CAN definitely answer for me, though, is is there a required distance from muzzle to chono for me to get accurate results? Caldwell says 10' - 15' or so for firearms, but I doubt this is applicable for airgunning. I'm shooting about 18" in front of the muzzle (when I'm not checking fps @ the target). Thanks again, and Happy St. Patrick's Day to you both as well! 
 
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Unless you have a test instrument calibrated by a certified calibration facility against a certified standard on a schedule specified by the certification facility the best you can hope for is a "ball park" reading and differences between models. The same applies to ALL instrumentation whether a $25 mechanical gauge or a million dollar piece of test equipment!
 
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