a month or so ago someone was asking about chronos in the SB and I related my experience from memory and I misremembered a bit so I wanted to attempt to correct that info, as I found my data from years ago and also repeated the experiment this week.
shot some rounds over two chronographs at the same time this week. The chronos were a "Chrony" and a "CED". They were positioned less than an inch apart and a little more than 10' from the muzzle.
The rifle was a 338LM and the breaks between the lines below indicate different loads as my friend with the 338lm is in the process of load development with several different bullet weights. So while the loads aren't all that great, they are informative about how the chronographs compare. I'll leave it to the reader to draw any possible conclusions.
The max difference across 15 rounds was 18 fps. That is 0.63% of the mean of the 15 rounds.
The mean difference of the 15 rounds was 5 fps. That is 0.18% of the mean of the 15 rounds.
chrony CED delta
2928 2926 2
2938 2929 9
2928 2928 0
2494 2494 0
3007 2989 18
3012 3000 12
3009 3002 7
3014 3009 5
2704 2696 8
2681 2674 7
2679 2678 1
3043 3039 4
2833 2817 16
2813 2804 9
2796 2790 6
I found this interesting because I did this test using a different shooting chrony in 2005. The only difference in tests was that they were spaced about 6" apart. However, I found in that test the CED recorded consistently higher velocities, with the summary as follows:
A sample 15-shot group has the following
Max difference 45 fps
min difference 35 fps
Mean difference 39.5 fps
Std. dev. 3.4 fps
Next week, a friend is supposed to receive an RCBS chrono and I plan to shoot over all 3. I'll report back if the results are interesting.
shot some rounds over two chronographs at the same time this week. The chronos were a "Chrony" and a "CED". They were positioned less than an inch apart and a little more than 10' from the muzzle.
The rifle was a 338LM and the breaks between the lines below indicate different loads as my friend with the 338lm is in the process of load development with several different bullet weights. So while the loads aren't all that great, they are informative about how the chronographs compare. I'll leave it to the reader to draw any possible conclusions.
The max difference across 15 rounds was 18 fps. That is 0.63% of the mean of the 15 rounds.
The mean difference of the 15 rounds was 5 fps. That is 0.18% of the mean of the 15 rounds.
chrony CED delta
2928 2926 2
2938 2929 9
2928 2928 0
2494 2494 0
3007 2989 18
3012 3000 12
3009 3002 7
3014 3009 5
2704 2696 8
2681 2674 7
2679 2678 1
3043 3039 4
2833 2817 16
2813 2804 9
2796 2790 6
I found this interesting because I did this test using a different shooting chrony in 2005. The only difference in tests was that they were spaced about 6" apart. However, I found in that test the CED recorded consistently higher velocities, with the summary as follows:
A sample 15-shot group has the following
Max difference 45 fps
min difference 35 fps
Mean difference 39.5 fps
Std. dev. 3.4 fps
Next week, a friend is supposed to receive an RCBS chrono and I plan to shoot over all 3. I'll report back if the results are interesting.