How do I measure my ft lb
- Thread starter jt-outta-cali
- Start date
[pellet weight in grains] * [velocity in fps]^2 / 450437
example for 18.13gr pellet moving 900fps:
18.13 * 900^2 / 450437 = 32.6fpe
example for 18.13gr pellet moving 900fps:
18.13 * 900^2 / 450437 = 32.6fpe
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FPE= Velocity squared * Weight of projectile / 450240
Velocity in FPS and Weight in grains
There are also online calculators if you search FPE calculator
Velocity in FPS and Weight in grains
There are also online calculators if you search FPE calculator
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I use this site,..just plug in your Velocity and ammo weight :
shooterscalculator.com
ShootersCalculator.com | Bullet Energy Calculator
Calculates the kinetic energy of a bullet. May also be used to calculate the muzzle energy of a rifle or handgun cartridge and compare it to other cartridges.
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Muzzle Energy Calculator | FPE Calculator
Use our Muzzle Energy Calculator | FPE calculator to compare different velocities and grains... Obtain multiple velocities from different gun settings or any other combination you want to compare with our FPE calculator to calculate muzzle energy. Foot pounds of energy from a pellet or rifle is...
nielsenspecialtyammo.com
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I use either the online calculators, usually on AoA’s website, or the FX Pocket Chrono will give you instant feedback if you enter the pellet weight.
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Well, those calculators are way better than shooting yourself in the foot then dropping weights on it to see which one feels the same. 
Sorry, couldn't help myself.
Sorry, couldn't help myself.Upvote 0
If it's a calculation you think you'll need more than twice, my recommendation is go ahead and plug the equation into a spreadsheet. I put all kinds of common calculations into a spreadsheet that stays open all the time...so quick and convenient to use.
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Until we have a fpe legal limit in the United States, I don’t give two craps about fpe. My guns shoot X grain projectiles X fps. No need to do senseless math and backwards math.
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There's some really good calculators online, a quick google search (not being sarcastic) but the top 3 when I googled FPE calcs have worked great so far for me.
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Or the simple method, gun goes poof, hole in paper or hole in ...insert critter here...critter becomes a subject in a picture next to your gun. Yeah, it's another offshoot of the rabbit hole as we all attempt to emulate PB's with a puff of air.
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Don’t forget about the scopes “eye box or pupil diameter”. You need to have all the data to come up with an accurate summation.
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Mainly trying to compare two air guns and also one of them has a power adjustment so I wanna see if medium is good for squirrel or if I need to stay on high
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I recommend reading the following thread. In it you’ll see a variety of opinions and things to consider regarding operation, ease of use, cost, reliability, etc.
Yesterday i asked if chrono is needed. Now i want to know if to buy FX, Caldwell or something else and why?
Yesterdays post: https://www.airgunnation.com/threads/how-important-is-it-to-own-chronograph-if-you-tune-your-gun-and-why.1272293/
www.airgunnation.com In it you’ll also see my take which is that despite having two other more expensive and fully-featured chronographs, the one I use the most is an inexpensive (~$35) clamp-on.
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I've had an FX Chrono since they came out. Pair it with a smart phone or tablet and you're all set. Attach to you barrel about 3" behind the muzzle (I used velcro tape for my setup) or find a way to place it beside and you're all set. And yes - I hook it right on the barrel - I don't shoot for groups when I'm tuning.
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Of course I do. How fast or slow you’re slinging are important numbers for tuning and ballistic data. FPE in our wimpy guns is not. It’s too vague. If you and I have the same gun and you want to know where I found the best results, would you like me to reply I found my best results at 78fpe? Then you have to start guessing what I’m shooting. Am I shooting 43gr at 900 or a 32gr at 1,050fps. To me it’s just vague lazy talk. The only time I would concern myself with FPE is if I would be taking body shots on big game with a big bore.
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A lot of the forum members use their airguns in competition. Many of the various types of airgun competitions have FPE limits. Usually maximum FPE, but sometimes minimum. FPE is a critical number when working on a tune for those uses.
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