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Re: chronograph accuracy...

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07 September 2004, 15:53
475/480
Re: chronograph accuracy...
Here in Houston after about 10 am my chrony gives high inconsistent readings ,I assume it is the angle of the sun on the unit.This happens all year long.
Sean
07 September 2004, 15:33
Bobby
A few years back I owned both a Oehler 35P and a Chrony. If you're familiar with the Oehler, it uses three sky screens and takes a velocity reading between the first and second screens and between the first and third screen. It verifies that the readings match and are valid. The sky screens can be placed at any spacing you like, most use a 10' piece of conduit, or 5' spacing. It's a really neat setup. The Chrony on the other hand is a simple unit with two sky screens and they are 12" apart. One day at the range I put the Chrony inside the spacing of the Oehler's screens, between the first and second screens, essentially taking 3 readings for every shot. What I found was pretty impressive. The little Chrony was NEVER off by more than 1 fps on any shot. The Oehler cost in the neighborhood of $350, the Chrony costs around $75. Well, I can tell you one thing, I sold the Oehler. It was bulky to transport, expensive and hard to setup. The Chrony, you unfold it put it on a tripod and attach the diffusers, and you're ready to go. It also transports in a case no bigger than a pistol case.
So, as to accuracy, they're accurate as all get out, even the cheap ones.
07 September 2004, 15:31
D Hunter
Hart, My Beta chrony did the same thing. I fooled around with it and sent it back twice and they completely replaced it and still get readings when it wants to give them and not when it doesn't. Previous post seem to be accurate as I have two buddies with the same product and it never fails to give them numbers. I replaced mine with a Oehler p35 this year and I do indeed get numbers in all lights with each bullet. I just don't have time to spend half a day packing all my crap up, drive nearly an hour to a range, try to check out loads for two or three guns and not get numbers to go with the loads. Then what do you have? You still don't know if your loads are any good or too warm or what. I am sorry I waited to get a good piece of equipment and wasted a couple of years putzing around with a cheap one that refused to deliver the goods. If you got a good Beta Chrony, more power to you. Life is just too short to put up with stuff that will not perform for me. "D"
07 September 2004, 11:44
hart
Quote:

I have tested Shooting Chronys by lining two up, and shooting through both. From the average difference between the two, you can calculate the random error in the system. It is only a few fps.

As long as it is a sunny day, or if the clouds are thin enough that you can see the shadow of your tripod, your readings will be very consistent, and probably very accurate.

If you leave the sky screens in place as the clouds thicken, you will get low readings.




Interesting. I have been frustrated with low and non readings from my Chrony. Last time I used it, about two months ago, the sun was fairly high in the sky (southern BC), and it would not read at all with the sun out. Every time the sun went behind a cloud it would read again. Even taped some cardboard flaps to the upright rods so that the eyes would be in the shade, but even that did not help. Coloring the bullets black with felt marker also did not help.

Do you find that your readings are similar when you use the sky screens on bright days and without on cloudy days? Usually I always us the sky screen. Maybe that explains the variations in day to day readings of sometime around 100 fps with identical loads. I'll have to pay more attention to weather conditions, and make notes accordingly.

I've been toying with the idea of placing the Chrony in a long translucent tube to see if that would help with reliability and accuracy.

Hart