Chrono info

[Handsome Rob]

Can anyone tell me, do chronos misread as the battery gets low on power?

I was testing loads yesterday & was getting very odd velocities. I tried some loads in the .280ai with 139gn. Powder type was exactly the same as I use for 162gn but obviously, loads were different. I noticed that the same load I use for the 162s gave me pretty much the same velocity with the 139s

I was expecting the 139s to run a couple of hundred fps faster than the 162s but velocity read as almost identical.

As I was packing up the low battery warning came on. I always assumed that electronics worked or they didn't

Did I break physics?

Edited February 10, 2017 by robtattoo

[mikegideon]

My guess is that it wasn't the batteries. But, the quickest answer may come by repeating everything with fresh ones. I have had a few unexplained inaccuracies with an optical chrony. Never could get 458 SOCOM to read reliably wth a chrony that was dead nuts with 223. Tried several times. Still not sure if any of the 458 velocities were right. And yes, I set it way back from the muzzle.

[tmauto769]

with mine, I always seem to have inconsistent readings with .223. With loads that should be hovering around 3100fps, I usually see 2600-2700. It seems to be close with published loads in 9mm though. This was with 2 different chronys, as I shot mine, combined the parts from mine and a buddy's to make one good one, using his housing and sensors. .22lr seems to be close to what is printed on the boxes. But I have never seen mine deviate when the battery is getting low.

[mike_f]

I had a similar situation with my Pact 1 chrono (that I bought around 1990).  On one range trip I was getting velocities about 100 fps faster that I normally had with the same loads, from the same guns, with the same chronograph. 

Since the chronograph was over 20 years old at that point, I called Pact to see if it need to be checked, recalibrated, or something similar. The gentleman I spoke with said, on the Pact 1 anyway, that there wasn't any calibration or adjustments required or possible. So I asked about out of spec/low batteries and was told that it either works or it doesn't - if it turns on and runs then the batteries aren't a problem. 

[ttocswob]

My Pro Chrono doesn't like snubby loads, too much blow-by. Also won't always pick up shiny bullets, and/or bright sunshine. A little black Magic Marker on the bullet helps. Had a string of 9mm rounds once that read over 2800 fps. No explanation for that one.

[frankmako]

i base my info from what my 1985 model chronograph does.  it either comes on and work or not.   to much sunlight can cause most problems.   heavy overcast skies can cause problems.   but i would change out the battery anyway to make sure.  

[mikegideon]

1 hour ago, ttocswob said:

My Pro Chrono doesn't like snubby loads, too much blow-by. Also won't always pick up shiny bullets, and/or bright sunshine. A little black Magic Marker on the bullet helps. Had a string of 9mm rounds once that read over 2800 fps. No explanation for that one.

That's what I have. I also have a magnetospeed that is real accurate. Just won't work physically in every case