Range Report Chronograph accuracy question

[Unsichtbar]

Re: Chronograph accuracy question

20 Degrees difference, shooting a reported temp. stable powder IMR 8208 Xbr. I figure difference in length .66" aprox. so 48.66" instead of 48"

 

[Lumpy Grits]

Re: Chronograph accuracy question

20* is part of it. Was it the same time of day and the Sun in the ,more or less, same spot?
Same can/lot of powder?
Hint; When was the last time you cleaned the crono's lens?
Respectully,
LG

 

[Unsichtbar]

Re: Chronograph accuracy question

IR screens were used, same can of powder, 7 days between shoots, then sensors happend to be brand new on first test 7 days before( had to buy a new pair, loaned to a friend that missed)there was a wind on the second test that might have interfered with the sensors being moved around but the readings were consistant about a 100 Fps difference not random error. Barrel had 40 rounds down on first test, barrel was not cleaned.

 

[doc76251]

Re: Chronograph accuracy question

For General Consumption:
One thing to remember w/ any chrono is that there is an acceptable "error" usually .005 fps for better models. If you multiply .005 X 2700 = 13.5. That's a 13.5 fps "error" built in to the system if the boolet is running a nice even 2700 fps. I have shot spreads of less than 13.5 but give the fish eye to those that claim "5 fps ES all day every day".

FWIW My CED M2 also seems a bit slow against plotted dope on a calibrated optic / range. I may have to try knocking the end caps off and see what it yields.

The IR screens are also high on my list of things to get.

Cheers,

Doc

 

[skurtz]

Re: Chronograph accuracy question

Was it clear or overcast?
My CED will give you different readins depending on the light conditions. I always make sure there isn't any sun shining directly on the sensors. I use masking tape shade the sensor if I can't turn the chrono in a different direction.