When others are talking about ft/lb energy is there a common or specific pellet weight that is common to determine that value? Different weights would change this value. In some instances it can be significant at least in my mind?
Tuning Ft/lb vs pellet weight
- Thread starter Brian T
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There's a formula (and multiple on-line calculators) that will give you the ft/lb (FPE) of a weight (projectile) traveling at a specific speed.
This is often referred to as the Muzzle Energy.
This is often referred to as the Muzzle Energy.
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When I refer to my rifle's ft/lb energy it provides the reader with an idea of how much pep it has with the optimum pellet already.
Certain platforms have average ft/lb energy and average pellet weights that are common values.
These are my averages I expect from PCP's.
.177 = 20 ft/lb
.20 = 20 ft/lb
.22 = 30 ft/lb
.25 = 45 ft/lb
.30 = 100 ft/lb
Springers are usually 18 ft/lb or less.
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Yes i know about the calculation. Perhaps im not explaining well...if I we're to shoot a 7gr pellet vs 10gr pellet the ft/lb difference can be over 4 ft/lb.
In my scenario im tuning to achieve 12 ft/lb. Different springs and/or different pellets will get me there but is there a preferred pellet weight to tune a gun .
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It doesn't rely on a single standard pellet weight, but rather it is calculated based on the specific weight of the pellet being used at that time.Energy measured in ft/lb (foot-pounds) is a measure of kinetic energy. It indicates how much force is transferred to the target when a projectile (such as a pellet) is fired.
The standard procedure is as follows:
The actual velocity is measured (using a chronograph) with a pellet of a known weight.
The energy in ft/lb is then calculated for that specific weight.
Conclusion
There is no "standard" or "typical" pellet weight for determining energy in ft/lbs.
The weight of the pellet used must always be specified to accurately calculate or interpret the energy value.
Manufacturers sometimes publish energy values using "standard pellets," but they don't always specify which type of pellet they used, which can lead to confusion.
If you switch to a heavier pellet (18 grains), the speed will decrease, but the energy output may be similar or even higher, depending on the situation.
Why can a heavier pellet generate more energy (ft/lb), even if it has a lower velocity?
Let's assume you have two pellets:
Pellet A: 14.3 grains at 800 fps
Pellet B: 18.0 grains at 730 fps (heavier, but slower)
Result: Although pellet B travels slower, it has more energy because it is heavier.
The standard procedure is as follows:
The actual velocity is measured (using a chronograph) with a pellet of a known weight.
The energy in ft/lb is then calculated for that specific weight.
Conclusion
There is no "standard" or "typical" pellet weight for determining energy in ft/lbs.
The weight of the pellet used must always be specified to accurately calculate or interpret the energy value.
Manufacturers sometimes publish energy values using "standard pellets," but they don't always specify which type of pellet they used, which can lead to confusion.
If you switch to a heavier pellet (18 grains), the speed will decrease, but the energy output may be similar or even higher, depending on the situation.
Why can a heavier pellet generate more energy (ft/lb), even if it has a lower velocity?
Let's assume you have two pellets:
Pellet A: 14.3 grains at 800 fps
Pellet B: 18.0 grains at 730 fps (heavier, but slower)
Result: Although pellet B travels slower, it has more energy because it is heavier.
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Typically 177 shooting 12 ft-lbs the go to pellet is the 8.44 grain, alternates are 10.34 and 7.87 & 7.33 grains. In field target the 10.34's have been the new rage primarily because they shoot better than the 8.44's out of most barrels. But if the barrel could shoot 8.44's well then that is what you want, even the 7.33's offer some advantage due to velocity when shooting in the wind.
If you can tune the gun to any velocity to get 12 ft-lbs I would select whichever pellet shoots best out of that barrel starting with the 10.34's (unless you have a Steyr, Walther or AirArms FT rifle, then I would start with the 8.44's).
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It seems like people are referring to the pellet with the best groups for them, or the highest energy they can obtain after testing various pellets. It might be safe to assume the latter unless they specify otherwise, at least that is what I do.
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Thats up to you. Generally this is determined by accuracy since that is far more importaint than power.
Thats usually the one I will refer to. Whichever projectile i use the most. Like my .25 cal pistol will hit 65fpe with a 25gr pellet. They are so accurate, I have not done much testing with anything heavier. Though I know it would make more power with heavy projectiles.
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@Brian T , I think I understand where you're coming from though. Sometimes a company will list the FPE of their particular rifle without stating which pellet and weight are being used. When I see this, I play around with FPE calculators and plug in different weight pellets until I match the stated FPE. Probably not the best method but it helps me make sense of it.
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Manufacturers have made the fpe ratings kind of confusing, because a lot of them will give velocity for a very light pellet and fpe with a very heavy pellet, totally confusing the data.
FX is good about listing what barrel length, pellet and velocity, along with fpe, so you can get a good idea of power. On the other end of the spectrum Airmaks doesn't say a word about power, velocity, or fpe ??
The list that maxtrouble posted is a very good rule of thumb, and will give you some idea of what to expect of "average" rifles, but then we're seeing all kinds of upping the game.
FPE in a particular gun will be higher for heavier pellets. So if a 22 cal gun is listed with 50fpe potential, you would be prudent to assume they mean with 18gr or higher pellets. It's hard to get a usable velocity high enough to get say a 14gr pellets to 50fpe. 14gr @ 30fpe is 980fps and likely won't be accurate. But 18gr at 30fpe is 860 fps, and highly usable. We're talking pellets here, when you get slugs involved, then it's a whole new game, and a 14gr pellet at 980fps would probably pretty close to ideal.
It's complicated for sure.
FX is good about listing what barrel length, pellet and velocity, along with fpe, so you can get a good idea of power. On the other end of the spectrum Airmaks doesn't say a word about power, velocity, or fpe ??
The list that maxtrouble posted is a very good rule of thumb, and will give you some idea of what to expect of "average" rifles, but then we're seeing all kinds of upping the game.
FPE in a particular gun will be higher for heavier pellets. So if a 22 cal gun is listed with 50fpe potential, you would be prudent to assume they mean with 18gr or higher pellets. It's hard to get a usable velocity high enough to get say a 14gr pellets to 50fpe. 14gr @ 30fpe is 980fps and likely won't be accurate. But 18gr at 30fpe is 860 fps, and highly usable. We're talking pellets here, when you get slugs involved, then it's a whole new game, and a 14gr pellet at 980fps would probably pretty close to ideal.
It's complicated for sure.
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You're correct regarding pcps. Piston guns are a different animal. Broadly speaking raising pellet weight generally decreases the energy.
IMO accuracy should always be priority. Energy is only really important if you're hunting. For hunting you need to find an accurate pellet that produces near your guns maximum power. Most mid power 177 piston guns are most efficient (power) with ~8 gr pellets. Only testing with targets and a chrono will tell you star works best in your rifle.
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Most of the references to FPE that I recall reading in this sub-forum include details on the pellet used. If that detail is not included, I don't pay much attention, because as you mention, FPE will vary with pellet type and weight. In my spring guns, the delta in FPE between JSB 8.4s and JSB 10.3s is usually about 0.5fpe, with the 8.4s being higher.
R
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You'll probably want to start with the 8.44's then, I believe that is what most field target shooters shoot out of springers.
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Which gun? ARH actually has an adjustable power kit for some of the HW platforms. Spring, guides, and a set of shims to adjust power. For .177 only. Considering trying it out in an old HW77. Easy way to adjust power once you find your most accurate pellet. The JSB 8.44 other mentioned work well in many of my 12’ish FPE guns. H&N FTT do the trick in the others.
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So I just watched a video about 12ft/lbs, and he mentioned that generally using lighter pellets in a springer gives you higher energy. He also mentions that for pcp its the other way around and that heavier pellets give more energy for pcp. Here is his video that I'm referring to.
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