Is there any formula to calculate the FPE at distance if I only know the muzzle FPE, fps and the weight of the pellet?
How to calculate FPE at distance?
- Thread starter Kavliaris
- Start date
Yes but it involves calculating all of the ballistics so that you know the velocity at that distance. You'd be better off to use chair gun or strelok to do that.
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Put the chronograph at the distance you want it measured at. Just don't hit the chronograph. Yeah easier said than done. 
Allen
Allen
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I wonder if a fx chronograph could be place somewhere near a target with cell phone close enough to get bluetooth of the unit thus getting speed of impact and as well as full string. 
Allen
Allen
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I tried that once and no it did not work. I was zipping them dangerously close to the top of it tooI wonder if a fx chronograph could be place somewhere near a target with cell phone close enough to get bluetooth of the unit thus getting speed of impact and as well as full string.
Allen
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Come to think of it, I was shooting at a bit of a downward angle there. It may work shooting on a more level plane but I have my doubts. The LabRadar uses a microphone to start recording I believe. The FX Chrono may work in a similar fashion.Glad someone else tried it already.
Allen
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How close to target was it? Maybe too close? I may fart around with it later this weekend just to try it. Maybe put a brick or cinder block in front of it to prevent damage.
Allen
Allen
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35-40yds give or take? It was awhile ago so I really don't recall. No target after it though. I was just putting my shots over the top of it and trying to keep them close.
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I think I figured out why you could not get your fx chronograph to work. Speed, you did not take into account how much lost in speed you would lose. At first I could not understand why it would not work. Then I realize you may not have change the reading speed to sub 12 UK speeds. As they read lower speeds. Or you may not be aware of how quickly a pellet can slow down in just 30 yards. I put the fx chronograph about 3 to 5 feet away from the target and my phone about 25 yards from that. Then I shot at 33 yards away about 840 fos I think. this is what I got.
Allen
this is what I got. Allen
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Well I'll be darned. I think you are absolutely right! I'll go about it again tomorrow and set it at a lower velocity. I'm kind of excited now to actually figure out my BC without buying new equipment! Thanks for the tipI think I figured out why you could not get your fx chronograph to work. Speed, you did not take into account how much lost in speed you would lose. At first I could not understand why it would not work. Then I realize you may not have change the reading speed to sub 12 UK speeds. As they read lower speeds. Or you may not be aware of how quickly a pellet can slow down in just 30 yards. I put the fx chronograph about 3 to 5 feet away from the target and my phone about 25 yards from that. Then I shot at 33 yards away about 840 fos I think.
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Allen
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There are so many variables with the arithmetic most of which are only wild assed guesses that your results will very likely be meaningless. The only way to do this accurately is to use multiple chronographs measuring the same pellet at several distances at the same time. If you can arrange that, you can also calculate the real ballistic coefficient for you, your kit and your environment. Anything less is a WAG, but maybe that's good enough. In the end, you really do not care about numbers. The only thing that really matters is where your pellet hits at various distances. So measure that and be done with the rest.
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Thank you, this does seem most likely the easiest means at a given distance. Just need acquire the chonograph......
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I use a cheap Chinese chrono set in front of a trap at 25yds. Unfortunately, the one I have is not so cheap anymore.
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