Collecting the Data: Chronographs Part 2

In Part 1, I went over the two Chronographs I have. I shot both tonight side by side to collect data and compare how they compared to each other.

Now some information on the setup:

The Rifle


I put my 20″ National Match Upper my good friend built for me on the SLW Barrel Shootout Lower (so I could function test it). The Upper features a 20″ Satern 1-7.7 twist barrel with a 223 Wylde chamber and is probably my most accurate semi-auto rifle. I like to use it to ‘proof’ ammo for both velocity and accuracy. I have a Vortex Viper PST 6-24 mounted on top with an American Defense Manufacturing 30mm QD Mount.

The Ammo


I used Magtech (CBC) 5.56x45mm 77gr HPBT Ammo. It is one of the cheapest ‘match’ ammo’s available and has proven to be very consistent and accurate for me in every rifle I have tried it in.

The Conditions

Conditions are important to note as my results here in Iowa at 780 feet will differ greatly from another persons results shooting in Idaho at 7800 feet. I always write down the conditions (to the best of my ability) when shooting at long range or testing ammo. This can be helpful to identify how ammo performs in a wide variety of conditions, both temperature variations and altitude changes.

The conditions were as follows

62 Degrees F

51% humidity

30.25 in/hg

SE 8mph

780 feet Elevation


I shot 2 series of 10 shots each, below are the excerpts from each device and the results shot by shot as well as each units calculated ES and SD. The deviation column shows the change between the previous shot and the current shot for each device to give an idea how they track.

Series 1

LabRadar Magnetospeed
Shot ID V0 Deviation Deviation
1 2833 1 2856
2 2830 -3 2 2841 -15
3 2818 -12 3 2833 -8
4 2784 -34 4 2844 +11
5 2774 -10 5 2845 +1
6 2803 +29 6 2850 +5
7 2814 +11 7 2833 -17
8 2789 -25 8 2828 -5
9 2814 +25 9 2830 +2
10 2798 -16 10 2814 -16
Stats – Average 2806 fps 2837 fps
Stats – Highest 2833 fps 2856 fps
Stats – Lowest 2774 fps 2814 fps
Stats – Ext. Spread 59.04 fps 42 fps
Stats – Std. Dev 18.55 fps 12.2 fps

series-1

Series 2

LabRadar Magnetospeed
Shot ID V0 Deviation Deviation
1 2806 1 2864
2 2831 +25 2 2902 +38
3 2778 -53 3 2809 -93
4 2820 +42 4 2798 -11
5 2828 +8 5 2829 +31
6 2824 -4 6 2841 +12
7 2818 -6 7 2826 -15
8 2813 -5 8 2851 +25
9 2802 -11 9 2821 -30
10 2803 +1 10 2839 +18
Stats – Average 2812.26 fps 2838 fps
Stats – Highest 2830.73 fps 2902 fps
Stats – Lowest 2778.47 fps 2798 fps
Stats – Ext. Spread 52.26 fps 104 fps
Stats – Std. Dev 15.68 fps 29.6 fps

series-2

 


I will be posting the complete data from both devices on the Chrono Data page on the top of the page.As you can see, there are some differences. Both are fairly close on ES/SD and average velocity.

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