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JG BAR 10 Over Joule

  • 26-02-2012 05:36PM
    #1
    Digy123
    Registered Users, Registered Users 2 Posts: 846 ✭✭✭


    Hey Guys I have a JG BAR 10 Gspec sniper its over the joule on .20s i think by about 6 fps or something now why am i using .20s you may ask well because i havnt got any heavier BBS yet but i want to know will a heavier BB reduce this FPS?


«1

Comments

  • #2
    clubberlang12
    Registered Users, Registered Users 2 Posts: 1,507 ✭✭✭clubberlang12


    Heavier BB will reduce the FPS but will not affect the joule output. Legal limit must not exceed 1 joule or 328 FPS with 0.2g bb's. Changing the spring is fairly simple on bar10/vsr's so that would be what i would do in your case.


  • #3
    Inari
    Registered Users, Registered Users 2 Posts: 3,152 ✭✭✭Inari


    Yes, using heavier BB's will reduce the FPS, but your gun will remain an illegal firearm until it is modified to fire under 1 joule.

    FPS (feet per second) is, as the name suggests, a measure of speed and not power. Joules is the measure of power, so when a gun is firing over 328fps with a 0.20g BB, then your gun is firing at >1joule of energy, and thus it becomes an illegal firearm.

    The only time it becomes legally compliant is when it has been modified to fire at less than one joule of energy, preferably by changing the spring for a lower powered one


  • #4
    Digy123
    Registered Users, Registered Users 2 Posts: 846 ✭✭✭Digy123


    Okay any idea how much a spring would cost? and where i could get one?


  • #5
    andy_g
    Registered Users, Registered Users 2 Posts: 7,562 ✭✭✭andy_g


    Digy123 wrote: »
    Hey Guys I have a JG BAR 10 Gspec sniper its over the joule on .20s i think by about 6 fps or something now why am i using .20s you may ask well because i havnt got any heavier BBS yet but i want to know will a heavier BB reduce this FPS?

    yes but the fps becomes lower however if using for example .28 the fps is 280fps but is still 1J heavier the projectile the lower fps to joule rating.


  • #6
    Zomg Okay
    Registered Users, Registered Users 2 Posts: 1,169 ✭✭✭Zomg Okay


    It isn't the FPS reading determines whether or not a gun is legal, it's the Joule reading. A Joule takes mass into account so heavier BBs won't bring it under the limit.

    I'm not exactly sure how much a weaker spring will set you back but I'd guess at about €15.


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  • #7
    c28omzk7ihsxv0
    Closed Accounts Posts: 878 ✭✭✭c28omzk7ihsxv0


    Heavier weight BB's actually give a higher joule output.


  • #8
    horgan_p
    Moderators, Education Moderators Posts: 2,654 Mod ✭✭✭✭horgan_p


    Franklin Screeching Minefield wrote: »
    Heavier weight BB's actually give a higher joule output.

    Laws of physics say no.
    Heavier bb traveling slower still equals the same measure of energy.

    See here http://www.arniesairsoft.co.uk/?filnavn=/articles/fps_limits/fps_calc.htm


    Dex should be along soon with the pointy haired science bit explaining why.
    Unless he's blue in the face from explaining it ,in which case use the search box at the top of the page.


  • #9
    Witcher
    Registered Users, Registered Users 2 Posts: 16,497 ✭✭✭✭Witcher


    Franklin Screeching Minefield wrote: »
    Heavier weight BB's actually give a higher joule output.

    Ya hear some beauts on this forum.

    :pac:


  • #10
    Puding
    Registered Users, Registered Users 2 Posts: 6,261 ✭✭✭Puding


    Blay wrote: »
    Ya hear some beauts on this forum.

    :pac:

    tbh it is quite an easy misunderstand that people pick up, in airsoft everything is normal given as fps, the limit is normally stated as 328fps with .20g that then gets shortened to 328fps in most places and on sites when chronoing

    to a lot of people 328fps is the law as they know it, get it under that fps and you're legal is how they learn it


  • #11
    c28omzk7ihsxv0
    Closed Accounts Posts: 878 ✭✭✭c28omzk7ihsxv0


    Actually heavier weight bb's retain more momentum for longer and with a good hop they can go further than a lighter weight bb.


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  • #12
    c28omzk7ihsxv0
    Closed Accounts Posts: 878 ✭✭✭c28omzk7ihsxv0


    Blay wrote: »
    Ya hear some beauts on this forum.

    :pac:



    I can even show you some chrono proof. I myself was very surprised at this result considering I am currently studying physics...


  • #13
    Witcher
    Registered Users, Registered Users 2 Posts: 16,497 ✭✭✭✭Witcher


    Franklin Screeching Minefield wrote: »
    If you really want to see how wrong you are I can even show you some chrono proof. I myself was very surprised at this result considering I am currently studying physics...

    It's not about whether I'm right or not, the laws of physics are what matter here and your theory breaks them. Quite clearly the chrono is fcuked.


  • #14
    Puding
    Registered Users, Registered Users 2 Posts: 6,261 ✭✭✭Puding


    Franklin Screeching Minefield wrote: »
    Actually heavier weight bb's retain more momentum for longer and with a good hop they can go further than a lighter weight bb.

    all other factors remain the same and you change bb weigh the power output of the device is the same


  • #15
    clubberlang12
    Registered Users, Registered Users 2 Posts: 1,507 ✭✭✭clubberlang12


    The Joule output can more or less be explained as the force at which the bb is expelled from the barrel. It is nothing to do with the speed or the mass of the bb. It will change fractionally from shot to shot. Not because of the weight of the bb, but because of other effects from air seals and the fact that the rebound of the coil(the spring) may not give an exact pushing force each time. The speed will decrease with a heavier bb as there is more kinetic energy needed to pass the bb through the atmosphere. But the force at which the kinetic energy is delivered remains the same despite the weight of the bb. A heavier bb will travel further because it retains its kinetic energy for longer and can neglect the atmospheric forces that are working in resistance against it. Simple example is, if you were to throw a ball of paper or a stone. Which would travel further?

    An airsoft chrono is essentially flawed when calculating joule figures because it uses a speed figure to calculate the joule output. That is why you enter the bb weight each time before chronoing.


  • #16
    sliabh
    Registered Users, Registered Users 2 Posts: 2,011 ✭✭✭sliabh


    clubberlang12 wrote: »
    The Joule output can more or less be explained as the force at which the bb is expelled from the barrel. It is nothing to do with the speed or the mass of the bb.
    First part right, second part WRONG! WRONG! WRONG! WRONG!

    This should be part of a test people do whenever they buy an airsoft gun - "What is the relationship between energy, mass and velocity (FPS)". This is stuff is basic physics described by the equation:

    Energy = (0.5) x (mass) x (velocity x velocity)

    The gun provides the energy kick to the bb (which by Irish law is supposed to be no more than 1 joule). Because of the equation above changing the bb weight doesn't change the energy, it just changes the speed of that it leaves the barrel.

    A lighter bb means faster speed, a heavier bb means slower speed. But the energy remains the same as this is something that was given to the BB when the piston drove home.*

    Because it is easy to use we check the energy with a chrono - it logs the speed of the bb, and assuming you know (or haven't lied about) the bb weight it's trivial then to work back to the energy.

    The only way to change the energy output of an airsoft gun then is to tweak the performance of the gearbox and barrel. The easiest way is to change the spring. Take down the spring, and less energy is given to the bb, so for a given weight of bb then the shot will travel slower.

    BTW, all the other stuff here about momentum, retaining kinetic energy and so on is b.s. from a legal point of view. All the law cares about is the velocity at the end of the barrel. If it is over 1J it is illegal. End. Of. Discussion.

    Once you are legal, then you can get into endless discussions about how bb weights change flight time, shot consistency, accuracy and so on. But that is a player/performance thing. None of them have any relevance to the legal question of "is that gun under 1J".


    * Note that because of the equation the change in velocity is related to the mass by a square relation. So doubling the BB weight wouldn't mean the speed drops by half, but it comes down by a factor of 4!


  • #17
    clubberlang12
    Registered Users, Registered Users 2 Posts: 1,507 ✭✭✭clubberlang12


    Sliabh, you are misunderstanding the context of the second part of that quoted part. The speed of the bb is determined by the joule output. Not the other way around. Velocity is only achieved by a force of some kind. A pushing force is needed to create any kind of velocity(speed). Therefore, speed is a by-product of force.

    The mass of an object will determine the velocity of it. The joule rating remains the same. This is the crux of this whole argument. The weight of the bb has a bearing on its speed, which in turn is determined by the force at which it is expelled (joule). Joules are not measured in speed. It is not a speed figure. It is a measure of force.

    A 3.0g bb traveling at 328fps is not 1 joule. This is what i am saying. The law is actually with regard joules. We transfer it to a speed figure as it is easier to establish. The law is not a speed figure. Basically, speed or bb mass do not effect the joule rating as in a platform, the joule rating should stay the same.

    Edit: Thread here explaining. Example of the car engine is probably describes it simpler than i have.

    http://www.boards.ie/vbulletin/showthread.php?t=2055353665


  • #18
    clubberlang12
    Registered Users, Registered Users 2 Posts: 1,507 ✭✭✭clubberlang12


    BTW, all the other stuff here about momentum, retaining kinetic energy and so on is b.s. from a legal point of view. All the law cares about is the velocity at the end of the barrel. If it is over 1J it is illegal. End. Of. Discussion.

    See this is the problem. The law is not about the velocity of the bb. The law is with regard the force of the bb, ie - joule. We use a velocity figure as it is easier to calculate with the measuring devices we have. As i said, 328 fps with a .2g is not the same as 328 fps with a .3g bb.

    But as you said, this thread has got de-railed from the original question


  • #19
    sliabh
    Registered Users, Registered Users 2 Posts: 2,011 ✭✭✭sliabh


    Hi clubberlang12, my post isn't specifically a correction of you, but more to correct a lot of wonky things already posted, which are doing more to muddy the waters than make things clear.


  • #20
    c28omzk7ihsxv0
    Closed Accounts Posts: 878 ✭✭✭c28omzk7ihsxv0


    Energy output is the same or greater. Airsoft has too many variables to be called accurately. And by calling my brand new chrono (which gives the exact same reading as the site chrono) broken you are wrong. As you are by blaming the usual variables. I am merely giving my own findings which have been the same on more than one chrono.

    My readings were taken from a sniper rifle which has +/-2fps difference.
    With .2g it is consistently.88j
    with .25g it is consistently .92j
    and with .3g it is consistently .94j


    Also I don't know why ye are stating that .3g at 328fps is over 1j. That is obvious, surely there is no one that stupid here.....

    The increase could be down to the heavier bb going through the hop-up better thus creating less friction leaving the barrel with more energy.


  • #21
    c28omzk7ihsxv0
    Closed Accounts Posts: 878 ✭✭✭c28omzk7ihsxv0


    Puding wrote: »
    all other factors remain the same and you change bb weigh the power output of the device is the same
    As rory said- MOMENTUM, which is retained for longer because of the weight. The power being the same doesn't effect it. Also particular hops hop some weights better than others. My m4 (.8j) can outrange my G36c(.97j)
    M4 using .25g and the g36c using .2g
    Not referring to Joule output - just stating that heavier bb's travel further.


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  • #22
    sliabh
    Registered Users, Registered Users 2 Posts: 2,011 ✭✭✭sliabh


    Franklin Screeching Minefield wrote: »
    The increase could be down to the heavier bb going through the hop-up better thus creating less friction leaving the barrel with more energy.
    It should be chrono'd with no hop at all, so if you are doing it right this won't be an issue.


  • #23
    clubberlang12
    Registered Users, Registered Users 2 Posts: 1,507 ✭✭✭clubberlang12


    I'm sorry for helping this thread go off topic. But as Sliabh said, there should be no hop up applied. Unfortunately sometimes, different hop up rubbers in different chambers will give different air seals or even contact points with the bb, even with the hop up dialled off.

    But back to the bb weight increasing the joule measurement. To put it simply in terms of physics.......it can't. Joule (energy) is an initiating force. Velocity is created out of force and mass. The energy comes from the cylinder and piston. The factors will affect this are the air seal, air volume in cylinder and the recoil power from the spring. The velocity of the bb is a direct correlation between the force exerting the bb and the weight of the bb.

    The problem we have with chronoing is that the chrono is a speed measuring device. Joule's are not measured in speed. We have to retrospectively calculate the joules from the figures acheived by the chrono. If we were able to void outside influences such as hop up contact or variation in bb weight,etc we would get a near true joule figure. But we can't. The chrono is not an exact measurement as it may be milli-seconds out on its measurement which affects the recorded speed which in turn affects the joule figure. A rifle/aeg may actually have the same joule output each time from the cylinder but inaccuracies such as bb weight variation, resistance of hop up rubber, dirt in barrel, non exact chrono speed reading will give a different joule rating. Hence the difference in joule output.


  • #24
    Puding
    Registered Users, Registered Users 2 Posts: 6,261 ✭✭✭Puding


    hop up should be off because every hop up works on friction and friction lowers the speed of the bb and their for does not give an accurate reading of what the max energy output of the device is


  • #25
    Puding
    Registered Users, Registered Users 2 Posts: 6,261 ✭✭✭Puding


    Franklin Screeching Minefield wrote: »
    As rory said- MOMENTUM, which is retained for longer because of the weight. The power being the same doesn't effect it. Also particular hops hop some weights better than others. My m4 (.8j) can outrange my G36c(.97j)
    M4 using .25g and the g36c using .2g

    tbh im not going to argue with you because it is pointless, all over factors remaining the same a change in bb weight change the energy output of a device

    yes changing the weight of a bb will change how the device performs in terms of range and accuracy based on 101 factors but so will changing the brand off bb, that is not the point, we're talking about the energy output pure and simple


  • #26
    gerrowadat
    Registered Users, Registered Users 2 Posts: 3,230 ✭✭✭gerrowadat


    Sure if it's a bit hot just chrono it with a diet coke can instead of a coke can. Much more scientific.


  • #27
    c28omzk7ihsxv0
    Closed Accounts Posts: 878 ✭✭✭c28omzk7ihsxv0


    Puding wrote: »
    tbh im not going to argue with you because it is pointless, all over factors remaining the same a change in bb weight change the energy output of a device

    yes changing the weight of a bb will change how the device performs in terms of range and accuracy based on 101 factors but so will changing the brand off bb, that is not the point, we're talking about the energy output pure and simple

    I was merely mentioning about how different weight BB's hop differently as another person stated wrong.


    EDIT- Never mind - hop up - facepalm to self....

    I thought it was off, I was using my own rubber design which was hard to turn off.


    We can conclude power output does not raise nor fall with different weight BB's, perhaps it is the volume of my cylinder was the problem.


    Anyway, we should go back on topic.



    Mate instead of buying a new spring (Assuming it is just a little over the limit) just cut it a little. Like one ring.


  • #28
    bullets
    Registered Users, Registered Users 2 Posts: 4,612 ✭✭✭bullets


    Really folk's It actually depends on if the BB's used are African or European
    and if the user of the gun is Laden or unladen. :P

    ~B


  • #29
    Spook_ie
    Registered Users, Registered Users 2 Posts: 10,892 ✭✭✭✭Spook_ie


    I'm new to airsoft ( in fact it's my son who wants to play it ) but do I understand this correctly

    The legal measurement is the power of the gun i.e less than 1 joule rather than the FPS ( usualy quoted as 328 fps )

    So if you could get lighter BB's say 0.12 then the effective range would be increased because the FPS for 1 joule would be higher ( 425 fps ) with a lighter BB


    Or am I totaly wrong?


  • #30
    Inari
    Registered Users, Registered Users 2 Posts: 3,152 ✭✭✭Inari


    Spook_ie wrote: »
    I'm new to airsoft ( in fact it's my son who wants to play it ) but do I understand this correctly

    The legal measurement is the power of the gun i.e less than 1 joule rather than the FPS ( usualy quoted as 328 fps )

    So if you could get lighter BB's say 0.12 then the effective range would be increased because the FPS for 1 joule would be higher ( 425 fps ) with a lighter BB


    Or am I totaly wrong?

    Your range is not increased, but raw speed is. The lighter the projectile, the faster it travels...but the less stable it is. It can be more easily blown off course. The heavier the BB the better the range (typically) due to it having more mass, and holding its velocity more effectively. That is at least how I understand it; please correct me if I am wrong!

    FPS has nothing really to do with range, only how fast something gets there. For range you are looking at barrel upgrades (precision/tightbore barrels), and softer hop up rubbers :)


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  • #31
    c28omzk7ihsxv0
    Closed Accounts Posts: 878 ✭✭✭c28omzk7ihsxv0


    Inari wrote: »
    Your range is not increased, but raw speed is. The lighter the projectile, the faster it travels...but the less stable it is. It can be more easily blown off course. The heavier the BB the better the range (typically) due to it having more mass, and holding its velocity more effectively. That is at least how I understand it; please correct me if I am wrong!

    FPS has nothing really to do with range, only how fast something gets there. For range you are looking at barrel upgrades (precision/tightbore barrels), and softer hop up rubbers :)
    That and the shape of the rubber/nub.


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