If I want to shoot at an angle, say at birds in a tree, I can use ChairGun (Windows) to figure out how far my pellet/slug will go before it returns to earth, and how much energy it will have left to do any damage to unintended targets = PART 2. However, before that I'd like to know how much energy can be considered dangerous by a flying/ falling pellet. = PART 1 PART 1: How Much Remaining Energy Is Dangerous? So, what happens when a pellet drops down from the sky, obviously having some energy left...?
SKIN: The scientists have tried to find out how much energy and what speed a projectile needs to puncture skin.
Jussila in a dissertation gathered the following data:
.22cal diabolo pellet | 16.51gr weight
Energy needed to puncture skin = 2.22FPE (3.01J)
Velocity needed (with this weight) = 246fps Smaller pellets (.177) or pointed pellets can be said to concentrate their energy on a smaller area, which means they would need less energy to puncture skin. Larger calibers by the same token need more energy.
Source:
http://ssf1910.dk/document/info/balistik.pdf EYE: Other scientists wanted to know how much energy and what speed a projectile needs to puncture the eye.
Kramer and colleagues experimented with airgun BBs shooting them into pigs’ eyes. Here is what they found:
.170 caliber | BB | 5.5gr weight
Min. energy needed for penetration – for .177 cal! (50% or more often) = 0.74FPE (1.0J)
Min. velocity at target needed for penetration – for .177 cal! – and for this weight (50% or more often) = 246fps Source:
https://drive.google.com/drive/folders/0B_PmkwLd1hmbd3pWYVVJeGlGaFE Note that the part of the BB that contacts the eye is shaped just like a domed .177 pellet, so this is comparable to pellets as far as the test goes.
Note also that the smaller diameter of a .177 caliber in comparison to a .22 or larger caliber means more energy concentration to break the skin or the eye ball surface. A .22 domed pellet has about 50% more impact area than a comparable .177 pellet [area = pi time radius squared]. Therefore, one could then assume that more FPE is necessary for penetration. I would estimate that min. energy needed for penetration – for .22 cal!
– is
1 to 1.5FPE.
The likelyhood that a pellet shot at random to hit an eye is about as likely as.... (I'm lacking a good comparison, it's that tiny.)
So, now that we know how little energy our pellets should have left, let's see in Part 2 at what angle we need to shoot them to assure that energy level, and how far the will fly.
PART 2: Max. Range and Remaining Energy Here is one example, with step-by-step instructions how to do it: This is a wadcutter pellet with its
terribly low BC: RWS Meisterkugeln 14.00gr (.22cal) | ME = 30FPE | 0.010BC (1) In ChairGun (WIN), I enter the general data of pellet (as listed above).
(2) For the range, I enter a ridiculously high value, say 9999 yards/ meters. ChairGun will usually not accept that value but reduce it to something more realistic. In this case, to 220y (200m).
(3) Now I look at the ballistics table in ChairGun to find the range at which the pellet has less than 2FPE of energy left. In this case, 120y (100m). At 140y (125m) it has only 1FPE left.
(4) Then go to the drop-down menu:
Toolbox, and select sub-menu:
Maximum Range. (5) To make any changes in the window that comes up, I right click into the graph or the table (e.g., the type of chart, or changing the granularity of the degrees in the table).
(6) In the chart
Maximum Range (cf. pic below) I find the range of 120y (where my pellet has only 2FPE left). The associated angle that the barrel must be inclined to reach that range is about a 2º angle (line of departure, LOD), and for 140y it is about 3º.
So (for this pellet and power), if my barrel angle is 3º or more, my pellet will have less than 1FPE of energy left when it returns to earth. (7) The absolute maximum range is about 230y (210m). This occurs at 24º of barrel angle.
(Note: There is also a graph in ChairGun to show the terminal velocity, but somehow I don't trust it, something seems off with that function.)
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I'll supply a few more to see how things do get progressively more dangerous.
Here is second example, a pellet with a
mediocre BC – because it's a hollow point, middle weight, and for that it's actually not bad at all:
JSB Hades 15.89gr (.22cal) | ME = 32FPE | 0.023BC The pellet has less than 2FPE left at a range of 260y (230m) and beyond. And less than 1FPE at a range of 320y (290m).
ChairGun graph below: 3º barrel angle (LOD) or more gets the pellet out to 260y (230m in the chart) –
meaning that at 3º or more angle the pellet will have 2PFE or less when returning to earth. 5º barrel angle or more gets the pellet out to 320y (290m in the chart) –
where the pellet will have less than 1FPE of energy left. Maxiumum range is at an angle of 26º, around 450y (420y in the graph).
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Here is a third example, a
high BC pellet, middle weight:
JSB Domed 15.89gr (.22cal) | ME = 32FPE | 0.030BC Less than 2FPE left at a range of 380y (350m) and beyond. Less than 1FPE left at 420y (380m).
ChairGun graph below: 5º barrel angle (LOD) or more gets the pellet out to 380y (350m in the graph). And 7º angle gets it to 420y (380m).
This means that at 5º or more angle the pellet will have 2PFE or less when returning to earth, and at 7º or more angle the pellet will have less than 1PFE. Maxiumum range is at an angle of 27º (LOD), around 570y (510 meters in the graph).
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A fourth example, a much heavier pellet, with
an even better BC than the previous.
JSB Monster II 25.39gr (.22cal) | ME = 37FPE | 0.036BC Less than 2FPE left at a range of 440y (400m) and beyond. It doesn't get below 1FPE....
ChairGun graph below: 9º barrel angle (LOD) or more gets the pellet out to 380y (350m) –
meaning that at 9º or more angle the pellet will have 2PFE or less when returning to earth. Maxiumum range is at an angle of 29º (LOD), around 620y (560m in the graph).
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A fifth example will hit the ball outside the park, and with all the slug excitement of the past months I needed to include this one...!
. A middle weight slug with 22gr, with
a typical slug BC of 0.090 – which is extremely high when compared to pellets – shooting from a regular medium power PCP:
Slug 22gr (.22cal) | ME = 32FPE | 0.090BC (RA4) Even as far as a 1000 yards out (900m) the slug will still have 2.5FPE left! Even with only 32FPE at the muzzle.
Maxiumum range is at an angle of 33º (LOD), around 1100y (1000m in the graph). But even with only 10º angle the slug will go as far as 750m (820y). Yeah, when we shoot slugs we better watch out, I guess...!
Do your ballistics – draw your conclusions – and be safe!
Matthias
