I have been reloading for about a year now. My daughter gave me a F1 chrony for xmas. So I got to try it out today (cloudy, no sun) and have some issues. Loaded 10 230gr Hornady FMJ RN with 5.8 and 10 with 6.0 Unique.
For the 5.8 I forgot the 1st 3 readings but the last 7 were 622, 609, 754, 565, 341, 456, and 455. The 6.0 loads were 543, 475, 473, 449, 573, 406, 490, 437, 409 & 425. These were hand loaded as close as i could get them on a RCBS 10-5 scale (within .1 gr). COL set at 1.255 with a .469-.470 crimp. 3-4" groups at 25yds so accuracy for me was pretty good.
I'm guessing velocity on these should be around 750-775 and im thinking this is a chrony issue. I tried with and without the sun screens.
Not sure what to do from here.
Thanks, pitch

How far was the sensors from where you fired the gun?

My chrony actually works better on slightly cloudy days.

A good test is if you have a 22lr pistol. Shoot the cheap 22lr and you should be near the 1000 fps range. That way you can verify if it is you(the ammo) or the machine itself,

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Still Running Against the Wind

About 5 ft, thanks for the 22 tip

You're too close. The shock wave is activating the first screen ahead of the bullet and giving slow speeds.
Also be sure the sun does not shine directly into the sensors on bright days.

More than half the battle with chronos is learning the little quirks about setting them up in a proper location. A overcast day is perfect weather.

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Science plus Art

It would help if you would tell us what CALIBER gun you are using.

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WWSSD?
What would Skeeter do?

USER’S MANUAL

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WWSSD?
What would Skeeter do?

Looks like .45 ACP loads to me.

One thing I forgot to mention was to be sure the screens are set at the right distance and firmly locked in place. The chrono is a timer, and if the screens are loose or incorrectly spaced, the speeds will be off.

Don't be concerned when you start getting consistent readings if they don't match the load tables exactly. Your load in your gun on that day may be 50-100 off from a test gun.

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Science plus Art

Yes, does look like .45 ACP.

Still need to know barrel-length to run the numbers through Quickload.

Temperature would help too.

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WWSSD?
What would Skeeter do?

I think you are too close. I use 10' minimum for normal handguns but move out to the full length of the cord for rifle, especially hot loaded 45-70. Mine's a Beta Master with the remote readout. I would try 10 or even 15' and see how that works. My Shooting Crony has performed just fine if set up properly.

I have an Oehler 35 and I agree that the screens are too close. Muzzle blast will definitely affect the readings.

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Dick

I have experienced similar problems and agree with previous posts. Move the chronograph further away from the muzzle and you will begin getting reasonable, consistent velocities.

........................same here.

First thing is Thanks for the quick replies. I probably was too close. They are 45 ACP. 4" M&P 45 compact. Also ran some 22lr and data looked good. 22 Wolf Match target shot with a CZ 452 Varmit. Advertised at 1050 fps, for 10 rounds I got 1079 AV, 16.58 SD with 49 ES. Since I'm new at this how do those numbers look.

Quickload data

Attached Images

quickload data.jpg (71.4 KB, 38 views)

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WWSSD?
What would Skeeter do?

Forgot to mention this... During one chronograph session, I was shooting both of my 40 calibers - a Ruger P944 (4.25" barrel) and my S&W 4013TSW (3.5" barrel). The chronograph gave reasonable readings for the Ruger but gave erratic readings from the S&W. Mind you, this was using ammo from the same box, same day, same distance, etc. Moving the chronograph brought the S&W readings right in where they should have been. For some reason, the shorter barrel S&W requires slightly more distance to the chronograph.

Thank you for the quickload data.