![]() ![]() ![]() Without a chronograph your mostly left estimating, but programs like ChairGun come with a pellet database of popular choices with estimated BC figures. One pellet may be carrying 8 ft/lbs of energy at 50 yards, while the other could have dropped to 5 ft/lbs. For example, if you take long range shots at 50 yards with one pellet and they work great against a pest or game animal at that range, but the second pellet doesn't, then the BC can show you how much of that initial FPE has been lost. Since the energy is proportional to the velocity, if your projectile is traveling 100 fps less at 50 yards, then it will have less impact energy. Knowing the BC as well as your MV, you can plug those figures into ChairGun and it will show you how much lower your Point of Impact (where it impacted) will be than your Point of Aim (where you aimed) for the newer pellet without you actually having to fire it and see for yourself. So let's say you know your hold-over for a domed 7 grain projectile at 50 yards, but the other pellet is a little lower because it's dropped more velocity. This difference can be profiled as the "Ballistic Coefficient" and can be used in a program like ChairGun to help accuracy. Meanwhile, your second projectile could start at the same 950 FPS MV, with the same mass, but only be moving 675 FPS at 25 yards. If you have one 7.5 grain pellet and a Muzzle Energy (ME) of 13 ft/lbs, you zero it for 25 yards, and then you figure out the hold-over (how high over your target you need to aim to compensate for the drop at that range) you need for 50 yards, why won't another 7.5 grain pellet with the same 13 ft/lb ME shoot lower with the same hold-over? Some projectiles, by merit of their shape and form or other factors, shed their energy faster through the air, So your first projectile might start at a 950 FPS MV, but at 25 yards, will have slowed down to 750 fps. With that you can also determine your Ballistic Coefficient (BC). So you could say your rifle would have a 950 FPS MV, or that your rifle had 13 FPE. This would give you a Muzzle Energy of roughly 13 ft/lbs. Generally speaking, we know that the rifle will be shooting 7.5 grain pellets at roughly 950 fps, +/- 50 FPS. You can get this figure with a chronograph, but there are also rough estimates available that are useful to have in regards to these other terms.įor example, let's say you have a 1000 Feet Per Second (FPS) springer air rifle. ![]() It could be expressed in joules, netwons, etc. So would anyone agree or should we try to find an "Air Guns for Dummies" book.Īs others mentioned, Foot Pound Energy is a measurement determined by the mass of your pellet and its velocity. Now maybe it is just dumb ole me, but just maybe there are others out there that would like to what you guys are talking about when are using these terms. Well everyone knows that, wrong, they don't.Īnd then it hit me as I was watching some air gun reviews, they use a chronograph to measure the pellet speed. Now that is great except no one tells you where or how you get the FPS! This article or paper could explain everything so everyone can understand it.įor example, every column or article I have read for weeks now states "muzzle velocity" " FPS" and it goes on to tell you how to figure out your FPE or foot pounds of energy. Now I don't just mean, this word means this and this word means this. (Maybe there is something somewhere and I just don't know where it is located.) I believe it would be great if there was a "Learning About Air Gun Terminology and how it is used " in this forum. Muzzle Energy, muzzle velocity, FPS, FPE, velocity. As I try to learn more and more about air rifles and what it would require to hunt small and large game I find myself trying to understand the following terms. ![]()
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