Comparison of two chronographs in series ... Pro Chrono and CED M2.

[MCMXI]

I've wanted to do this for a while to validate the "accuracy" of my chronograph so after shooting a bunch of groups this afternoon, my friend placed his Pro Chrono in series with my CED M2. The Pro Chrono recorded velocities are shown in parentheses and the PC was behind the CED M2 (further away from the muzzle) but right up against it. Both chronographs seem to be in reasonable agreement. I have no idea which one is the more accurate and I suppose it doesn't matter really. I also don't know why the PC registered higher velocities for the .300 WSM but slower velocities for the .270 Win and .300 Win Mag. Does anyone else have comparisons of chronographs in series?

.300 WSM
3050 (3058)
3043 (3044)
3068 (3072)
3005 (3016)

.270 Win
3139 (3129)
3130 (3122)
3148 (3137)
3139 (3129)

.300 WM
3271 (3259)
3294 (3284)

 

[jmr40]

I'd say they are close enough to not cause concern. Just a guess, but slight changes in the angle and intensity of sunlight during the day can cause small differences in readings. I wouldn't worry about it, but do find it interesing. Might try it again and swap the chronographs and see how that effects the readings.

 

[Furncliff]

0.27 percent difference between the two chronys on the first shot. Sounds acceptable.

 

[tahoe2]

that's pretty cool stuff!! what's the price difference of those two?

 

[tryshoot]

I have wanted to know how accurite my crony is. Thank you for this report. Never seen a test like this.

 

[45_auto]

You're looking at a difference of 1/3 of 1 percent worst case. What do you expect for $100?

 

[BADUNAME37]

When you figure the chronies are "looking" at the bullet passing over, if one happens to see more of the bullet than the other one, there would be that much error in itself, discounting all other things.

Perhaps the difference between bullets is just the difference between how one chrony "sees" the pill passing over, as someone else noted, the sun, shadows, angles, etc. all play into this equation.

I also agree with others, for about $100. there really is not much to complain about.

I bet, even off of a sturdy bench and sand bags, a person could not shoot as accurately as the "ballistic-error" between the two readings.

 

[arizona98tj]

1858....thanks for taking the time to do the evaluation and post the results.

 

[medalguy]

I have 2 identical Chrony Beta Masters and just for fun I placed them end-to-end and fired a series of .308 rounds through them. I got about the same variances, +/- 5-8 fps at 2800 fps velocities, and consider them to be essentially identical.

 

[wally]

I'd wager a Student's T test would show no statistically significant difference between the means.

Not enough shots to make any point over one caliber being faster than the other and the situation reversed for a different caliber, such is the nature of random variations.

 

[MCMXI]

One of the reasons why I wanted to do this is that the CED M2 indicated that my match .308 Win load was about 75 ~ 100fps slower than I believed it to be based on data from a Shooting Chrony Beta Master that I'd been using for a couple of years. I figured that the CED M2 was correct based on required comeups when shooting at 200, 300, 500 and 600 yards so it was good to validate its output using another quality chronograph. I have access to another CED M2 so will make some more comparisons over the next few months. I can probably put three chronographs in series to see what the differences are.