I changed my mind about what I am going to talk about today. I was reading the definition of statistical significance and there is even some debate to whether it is actually accurate. You don’t want to see the math and you probably don’t even care about the esoteric aspects. In theory, significance validates the data set. Since I measured all of the data, my equipment is either working (data valid) or it is not (data invalid). I choose to believe that it is valid.
In lieu of a more complicated analysis, I am going to talk about the difference between two different pellet shapes. What is going on? I shot all of my pellets in one container so the ones I switched to had a different shape, see the picture below.
The pellet on the left is what I have been working with. The name given by the manufacturer in ‘Energy’. The one on the right is called ‘Hunter’. Both are 7.56 grains in weight and constructed of lead. In the course of gathering data I noticed an accuracy difference, see below. This is known as point of aim versus point of impact between two different pellets.
Looking at the target on the upper left, those were shot with Energy pellets. The X represents the point of aim and you can see that the results ring the point of aim. Switching over to the Hunter, I see there is a significant drop in the point of impact from the point of aim. My point here is ammunition is not always swappable with identical results.
To address this, I need to re-sight in my scope. For purposes of just getting velocity measurements, that is not important today but it is worth noting this is the case.
| Muzzle Velocity (fps) | Velocity @ 30′ (fps) | |
| 1 | 951 | 906 |
| 2 | 965 | 892 |
| 3 | 974 | 908 |
| 4 | 968 | 904 |
| 5 | 960 | 906 |
| 6 | 965 | 905 |
| 7 | 956 | 909 |
| 8 | 971 | 909 |
| 9 | 963 | 907 |
| 10 | 970 | 908 |
| 964.6 +/- 19.5 | 905.4 +/- 15 |
You will recall from previous weeks with the Energy pellet I got 955.8 +/- 30.3 fps and 857.3 +/- 22.2 fps. That is a percent difference of 0.91% and 5.45% respectively comparing Energy versus Hunter pellets at muzzle and 30′ readings. In my mind, the data says that muzzle velocity is about the same, however there is a clear velocity difference at 30′ between the Hunter and Energy pellets.
I think that it is also worth noting that my numbers are becoming more consistent. There is a pretty narrow window that the pellets need to travel to for the chronograph to read. I am estimating that my failure to read count has dropped by two thirds. So, I would say that I am getting better using the tool. Regardless, this is why we do math on the data. This is the term normalized.
End Your Programming Routine: You are now on your way to becoming an actual physicist. I didn’t publish a hypothesis before I started this but if I would have, I would have thought that the Energy pellet would have more velocity at 30′ than the Hunter based on shape alone. Since there are only two variables in calculating energy, mass and velocity and the mass is the same for both pellets, it seems like Energy is actually misnamed.
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