1. SubscriberAThousandYoung
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    25 Jul '11 19:11
    Could you take a carbine or pistol and give it a front sight post that can extend past the barrel to give a longer sight plane for the iron sights? What advantage would a longer gun have over such a system?

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  2. Cape Town
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    25 Jul '11 19:27
    Originally posted by AThousandYoung
    What advantage would a longer gun have over such a system?
    I think a longer gun allows the bullet to pick up greater speed, obtain its spin with less friction, and come out of the barrel with a more consistent direction.
    A pistol with telescopic sights would not shoot as far nor as accurately as a rifle.
  3. Subscribersonhouse
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    25 Jul '11 23:141 edit
    Originally posted by AThousandYoung
    Could you take a carbine or pistol and give it a front sight post that can extend past the barrel to give a longer sight plane for the iron sights? What advantage would a longer gun have over such a system?

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    The answer is no, the short barrel means the bullet will start to wobble after it leaves the barrel because the rifling inside the barrel won't have the same number of turns as a longer barrel and therefore the bullet will not be spinning as fast as a longer barrel. The faster the bullet spins, the less tendency there will be for wobble, because of gyroscope effect. Wobble in this case more precisely means 'precession' around the line of flight.

    Therefore a short barrel will impart less RPM's to the bullet as a longer barrel, therefore when the bullet leaves the short barrel, it will wobble slightly more.

    So the longer sight won't help because by the time the bullet reaches the distance of the extended sight, it will already be slightly wobbly, more than if the barrel and sight were the same distance.
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    26 Jul '11 12:29
    The answer is it depends... which the greater factor is in the accuracy of the shot...

    Over short distances it is typically the aim of the person shooting the gun rather than the inaccuracy of the round itself.

    As demonstrated in an episode of myth busters where they tried to curve shots like in the film 'Wanted',
    despite mutilating the rounds to make them unbalanced and removing all rifling they still passed through several tens of meters of paper sheets straight enough to have their course marked out with a laser pointer.

    Thus having a longer sight giving better aiming would tend to allow for greater accuracy.

    This would only apply to situations where the shooter is aiming down the sight.

    However handguns are usually more about speed of aim rather than accuracy of aim.
    you want to shoot before the other guy does.
    so you tend to be aiming with muscle memory not by iron sight.
    having a long sight extending off the end of your barrel would tend to hinder this.
    If you need that kind of accuracy your better off with a WYSIWYG laser sight and/or a rifle.
  5. Subscribersonhouse
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    27 Jul '11 15:51
    Originally posted by googlefudge
    The answer is it depends... which the greater factor is in the accuracy of the shot...

    Over short distances it is typically the aim of the person shooting the gun rather than the inaccuracy of the round itself.

    As demonstrated in an episode of myth busters where they tried to curve shots like in the film 'Wanted',
    despite mutilating the rounds to ...[text shortened]...
    If you need that kind of accuracy your better off with a WYSIWYG laser sight and/or a rifle.
    And a laser sight would have to have the beam adjusted for the distance of the shot.

    The bullet drifts down because of gravity so the further the shot, the more downwards the aim of the laser beam if you want to know where the bullet will hit as the bullet gets further and further away. And of course all that would depend on the velocity of the bullet, the mass and the charge in the round. I imagine you could have a computer calculate all that but I am not enough of a gun nut to know if that has been done for home use. That does not take into account windage, only gravity.
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    27 Jul '11 16:50
    Originally posted by sonhouse
    And a laser sight would have to have the beam adjusted for the distance of the shot.

    The bullet drifts down because of gravity so the further the shot, the more downwards the aim of the laser beam if you want to know where the bullet will hit as the bullet gets further and further away. And of course all that would depend on the velocity of the bullet, t ...[text shortened]... know if that has been done for home use. That does not take into account windage, only gravity.
    of course...

    However on the kind of distance scale where you stand a hope in hell of hitting the side of a barn with a handgun,
    The deviation from a straight line by either gravity or wind deflection is negligible.

    Over short ranges those factors are only relevant if you're a marksman trying to score a perfect 100 on a target shoot...

    In which case you are using a rifle anyway.

    Handguns are meant for use in close quarters where, once a given level of accuracy is achieved, how fast you get your shot off is the important factor.

    In these circumstances a simple laser pointer aligned strait down the barrel is more than adequate.

    (note: a low figure for muzzle velocity is 200m/s, a long range for a handgun is 20m. the distance the bullet will drop over that distance is (1/2)*a*t or 4.905mm in this case... I think we can agree therefore that gravity is not relevant to accuracy of handgun rounds over typical use distances)

    Once you get outside close quarters handguns are, in anything other than the hands of an expert marksman, almost totally useless.

    And a rifle of some kind is required...

    Note: A typical long barrel machine gun, in semi-automatic mode, would qualify as a rifle for these purposes.
  7. Subscribersonhouse
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    27 Jul '11 20:531 edit
    Originally posted by googlefudge
    of course...

    However on the kind of distance scale where you stand a hope in hell of hitting the side of a barn with a handgun,
    The deviation from a straight line by either gravity or wind deflection is negligible.

    Over short ranges those factors are only relevant if you're a marksman trying to score a perfect 100 on a target shoot...

    In whic ...[text shortened]... l long barrel machine gun, in semi-automatic mode, would qualify as a rifle for these purposes.
    Making up for inaccuracy by firing 800 rounds per minute, maybe 30 rounds or so, making it more like a serial shotgun.....

    I wonder if there is a maximum length you can make a barrel before you run into diminishing returns? I don't mean in terms of portability, I mean in terms of ultimate accuracy. Like a 10 meter barrel, would there be any benefit over what modern sniper rifles have now?

    I watched the military channel the other day and they talked about sniper shots getting the bad guys at a mile and a half.

    My guess is making the barrel longer than a sniper rifle would not do any good, just lower the exit velocity due to friction.
  8. SubscriberAThousandYoung
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    27 Jul '11 21:45
    Part of it has to do with having enough room for the powder to finish burning. That's why M4 carbines have -1 damage (I mean do less damage than full length M16s).
  9. Subscribersonhouse
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    28 Jul '11 00:41
    Originally posted by AThousandYoung
    Part of it has to do with having enough room for the powder to finish burning. That's why M4 carbines have -1 damage (I mean do less damage than full length M16s).
    You mean do less damage to the barrel itself? I have to admit other then the physics of the flight path I am pretty ignorant of the workings of rifles and pistols.

    I guess that answers my question about even longer lengths, say a 10 meter barrel, the burn would finish way before the bullet leaves the barrel and would then just start slowing down due to friction after the burn finishes.

    So the gist of that sounds like it would be you match the burn time to the barrel length so the burn finishes just as the bullet leaves the barrel.
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    28 Jul '11 14:02
    There is an optimum length of barrel for maximum muzzle velocity
    (and hence accuracy, as the higher the velocity the higher the potential accuracy)

    This optimum length is the length at which the the diminishing pressure from the explosive charge behind the projectile round
    is balanced by the increasing pressure in front combined with the friction with the sides of the barrel.

    if the barrel is longer than this then the round will begin to slow after this point...

    if the barrel is shorter than this then the round will still be accelerating when it reaches the muzzle and some of the charges energy will be lost.

    most guns and rifles are shorter than this optimum, handguns certainly are.
    Navel guns however do tend to this optimum length.

    One of the advantages of rail/coil guns (which are being looked into by the US navy) is that the accelerating force is constant and doesn't diminish as the projectile moves down the barrel,
    combined with the ability to vent air from the sides of the barrel as you don't need to make the barrel air tight thus reducing the pressure in front of the projectile.
    This means much higher muzzle velocities, and thus ranges can be achieved than with a traditional projectile weapon.
  11. Subscribersonhouse
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    28 Jul '11 14:591 edit
    Originally posted by googlefudge
    There is an optimum length of barrel for maximum muzzle velocity
    (and hence accuracy, as the higher the velocity the higher the potential accuracy)

    This optimum length is the length at which the the diminishing pressure from the explosive charge behind the projectile round
    is balanced by the increasing pressure in front combined with the friction muzzle velocities, and thus ranges can be achieved than with a traditional projectile weapon.
    You sound like quite an expert on the subject. My only experience shooting was when I almost offed my old man hunting for quail in California🙂 I was 13 at the time. I tended to not like guns after that. He was killed by a gun in a robbery much later so you can see how I feel about guns in general.
  12. SubscriberAThousandYoung
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    28 Jul '11 16:45
    Originally posted by sonhouse
    You mean do less damage to the barrel itself? I have to admit other then the physics of the flight path I am pretty ignorant of the workings of rifles and pistols.

    I guess that answers my question about even longer lengths, say a 10 meter barrel, the burn would finish way before the bullet leaves the barrel and would then just start slowing down due to f ...[text shortened]... ch the burn time to the barrel length so the burn finishes just as the bullet leaves the barrel.
    No I mean do less damage to the person who receives the bullet.
  13. Subscribersonhouse
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    28 Jul '11 19:26
    Originally posted by AThousandYoung
    No I mean do less damage to the person who receives the bullet.
    You mean like if the exit wound is 2 inches across vs 4 inches across? Wonder if that would make the person more alive, less dead🙂
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    28 Jul '11 21:47
    Originally posted by sonhouse
    You sound like quite an expert on the subject. My only experience shooting was when I almost offed my old man hunting for quail in California🙂 I was 13 at the time. I tended to not like guns after that. He was killed by a gun in a robbery much later so you can see how I feel about guns in general.
    I don't like guns either.

    I just understand the physics of how they work.
  15. SubscriberAThousandYoung
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    29 Jul '11 01:54
    Originally posted by sonhouse
    You mean like if the exit wound is 2 inches across vs 4 inches across? Wonder if that would make the person more alive, less dead🙂
    M4/M16s don't leave exit wounds. Exit wounds are a sign of an inefficient overpowered round.

    The difference between the M4 wound and the M16 wound is how much your insides have been shredded by bits and pieces of the bullet.
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