Hi everyone, I have a question concerning pellet speed vrs grains of a pellet. I purchased an FX Bobcat .25 cal from Airguns of Arizona and told them I wanted to shoot H&N hunter extreme 28.4 grain pellets. It came with a chrony shot string using those pellets at an average of 859 fps, since I don't have a chrony my question is what does adding 5 grains or subtracting 5 grains by pellet choice do to the pellet speed. Is there a way to get a rough estimate of a JSB Exact king 33.95 grain pellet or a H&N field target 19.9 grain pellet vrs the known speed of the hunter extreem ? My last post was before and after I purchased my Bobcat, post # 84706 if you want to look. Thank you for such a great place to read about our air gun sport.
FPS vrs grains
- Thread starter 509ajl
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You can estimate the speed of other pellets from energy level that your rifle producing with current set up. From my experience when you up in weigh you get little higher energy and when you lower weight of pellet energy lowers a bit, given everything else is the same.
You current energy is at ~46 FtLb with 28.4 grain pellets
With 33.95 I would estimate it aorund 810 FPS
With 19.9 about 940 FPS
You current energy is at ~46 FtLb with 28.4 grain pellets
With 33.95 I would estimate it aorund 810 FPS
With 19.9 about 940 FPS
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You can figure your muzzle energy by taking the pellet weight, divided by 7000. Take the muzzle velocity times itself, then take that answer and multiply it by the value from the pellet weight getting divided by 7000. Take that answer and divide it by 64.4. This will be your muzzle energy, at the muzzle, in ft./lbs.
You might already know this, but thought I would share it just in case.
You might already know this, but thought I would share it just in case.
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This is all great information, but know that each gun will shoot each round differently at different speeds accurately. So if you gun likes H&N at 859 it may not like JSB's or other pellets at that FPS or FPE. Pellet testing is where you will out exactly how much you rifle likes each pellet at what speeds. But you may know this already too.
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Thank you all for your answers, shutik you cut right through and gave me the estimated answers, perfect and thank you ! crosman, you gave me the formula to calculate any of my other pellet weights and that is like teaching me to fish, thank you as I didn't know that formula. I like this forum as I learn so much from it. ginuwine I thank you for your input also and yes I am going to try each pellet for its accuracy at each distance. I had a reason for asking the question about pellet speed and grain wt and that was to see if a light pellet would fly at a speed that would be stable out of my Bobcat and if a heavy pellet would fly fast enough to achieve a distance and now I can look at other material concerning pellet speed and distance. I have high and low settings on my Bobcat so low with light pellet and high with light medium and heavy pellet, four shot curves to map out in the future.
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Not sure if you know about this handy tool but it's indispensable.
https://www.pyramydair.com/airgun-resources/widgets/convert.php?Units&u=14
https://www.pyramydair.com/airgun-resources/widgets/convert.php?Units&u=14
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