Strange Chrony Data

[ChuckS1]

Looking for some corroboration on a theory I have. Let's see if anybody agrees with me.

Took my Chrony Beta out to the range today. Was shooting my 6" K-38 with a 358439 hollowpoint and loads with 3.5 to 4.1 grains of Bullseye loaded in .2 grain increments. The first couple of strings resulted in velocities in the mid-700's, which I was expecting.

Went downrange to change targets, came back, and the next three strings all had velocities in the 300-400 fps range. Knew something was up since I was testing .38 Special loads and had been working up in .2 grain increments, with the lowest loads starting out that read in the mid-700 fps range.

I turned the remote unit off, let it sit 5 minutes, turned it on. Fired another string and got velocity readings in the mid to high 800 fps range (which was the expected range). Next string after that the readings were in the 100-200 fps range, this time with the hottest load.

Weather was sunny, about 43 degrees, had the screens on. Was firing directly over both screens with the unit about 15 feet in front of me. Never shot the chrony once...

Without telling you guys what I think my problem is, what do you think causes the erratic readings?

 

[ChuckS1]

Looking for some corroboration on a theory I have. Let's see if anybody agrees with me.

Took my Chrony Beta out to the range today. Was shooting my 6" K-38 with a 358439 hollowpoint and loads with 3.5 to 4.1 grains of Bullseye loaded in .2 grain increments. The first couple of strings resulted in velocities in the mid-700's, which I was expecting.

Went downrange to change targets, came back, and the next three strings all had velocities in the 300-400 fps range. Knew something was up since I was testing .38 Special loads and had been working up in .2 grain increments, with the lowest loads starting out that read in the mid-700 fps range.

I turned the remote unit off, let it sit 5 minutes, turned it on. Fired another string and got velocity readings in the mid to high 800 fps range (which was the expected range). Next string after that the readings were in the 100-200 fps range, this time with the hottest load.

Weather was sunny, about 43 degrees, had the screens on. Was firing directly over both screens with the unit about 15 feet in front of me. Never shot the chrony once...

Without telling you guys what I think my problem is, what do you think causes the erratic readings?

 

[RidgwayCO]

Two possibilities spring to mind:

1) Weak battery (replace it)

2) Sun position (my Shooting Chrony doesn't like the sun overhead (from 11:00 am to 1:00pm)

In the interest of full disclosure, my Chrony also doesn't care for anytime on Thursdays, nor for odd weeks in leap years...

Seriously, my Shooting Chrony is now relegated to indoor work with the optional lighting fixtures and incandescent bulbs. It works great with those!

 

[Paul5388]

I'd say it's the battery also.

When you turn off the Chrony, the battery will "regenerate" to a certain degree. As it is used longer, the battery shows the continued drain and gives erroneous readings.

 

[Gun 4 Fun]

Originally posted by Paul5388:
I'd say it's the battery also.

When you turn off the Chrony, the battery will "regenerate" to a certain degree. As it is used longer, the battery shows the continued drain and gives erroneous readings.

+100

 

[John R]

Mine does this when the battery gets low.
When you shut it off the battery builds back up a little.

 

[ChuckS1]

Thanks. I was thinking it was the battery too, but wanted to rule out other things. I was shooting at 0930 and the sun wasn't above the trees yet when I started, but by the time it started acting goofy, I was getting some sunshine.

Anyways, bought some batteries on the way home, so I'll try again tomorrow.