Chronograph issues....

[SabreKiller]

I didn't want to hijack the other chrono thread, so I started another one.

I've got an old Pact Model 1XP chrono and I have had some issues with it lately and I'm looking for a little insight into my problem.

Problem #1-extreme variations in velocity. I'm talking several hundred FPS for a 22-250 and a 6.5 PRC.

Problem #2-it doesn't always give me a reading. No error or nothing.

This past weekend I set it up at the range to check some 6.5 PRC loads and some 7 mag loads. I fired 6 shots, 4 from the PRC and 2 from the 7 Mag and never got a reading.

Set up is 10 feet for the muzzle, new battery, the start and stop cables are installed correctly.

The only two things I can think of are it was a bright sunny day and the wind was blowing the skyscreens pretty good. Any help is appreciated. Thanks!

[Mike D]

My thoughts are you either have a failing or dirty sensor(s). Traditional Chronographs aren’t overly complicated. They just measure the time between the bullet breaking the sensor openings.


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[SabreKiller]

My thoughts are you either have a failing or dirty sensor(s). Traditional Chronographs aren’t overly complicated. They just measure the time between the bullet breaking the sensor openings.


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I'm guessing the start and stop sensors are what you're talking about and are located below the skyscreens. Is there any way to clean them off maybe? Alcohol and a cotton swab or something maybe?

Would the wind blowing the screens around have much effect? They were rocking pretty good from side to side.

[RifleBowPistol]

Probably not any big deal, but might be. The sensors can be very sensitive to light conditions. I had the exact same problems you are describing a while back. I was trying to shoot in too low of light. After multiple bad readings, more often no reading at all. I called it done and packed everything up and went in the house.

Sometimes if you are getting large variations in velocity, it's because you have the chronograph too close to the muzzle and the chronograph is measuring the muzzle blast and or gasses leaving the muzzle. Seeing you were shooting a 7mm Rem. Mag. that is a good possibility, if you only had the chronograph 10 ft. from the muzzle.

[Mike D]

I'm guessing the start and stop sensors are what you're talking about and are located below the skyscreens. Is there any way to clean them off maybe? Alcohol and a cotton swab or something maybe?



Would the wind blowing the screens around have much effect? They were rocking pretty good from side to side.

I would probably start with canned or compressed air. If the lenses are dirty maybe a Q tip with alcohol or something.


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