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Rifle verus smoothbore?

Discussion in 'Post-World War 2 Armour' started by Ebar, Apr 26, 2006.

  1. Ebar

    Ebar New Member

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    Okay before anyone says it yes I do grasp one has rifling and the other doesn't but what the difference? What are the pros and cons of each type? What the big deal?
     
  2. Notmi

    Notmi New Member

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    With smoothbore, you can use longer ammunition and therefore have bigger payload, thought fins take some weight and length.

    With rifling, you dont need fins and (usually) get better accuracy with dumb ammunition.
     
  3. Oli

    Oli New Member

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    Smoothbores require fin-stabilised ammunition, rifled guns don't (in fact rifled guns can't fire long rod pentrators with any precision - the spin affects the fin-stabilisation). Rifled guns need technical trickery to get the best out of HEAT rounds (spin degrades the jet).
    Brigadier Simpkin in some of his many books claimed that, contrary to popular belief, smoothbores are more accurate over long range than rifled guns and that a smooth bore was equivalent to having another 10 mm of calibre.
    Since pentration of modern (L/D 1:20 or greater) rounds is dependant largely upon the the L/D ratio then smoothbores have the advantage in anti-tank duties.
    Presumably they are also cheaper to make (no rifling required) and probably lighter (less internal friction will reduce barrel thickness requirements).
     
  4. Ricky

    Ricky New Member

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    And I'm guessing that barrel wear is less of a factor.

    btw - couldn't they cure the fin-stabilising issue by having the fins set at an angle, so they do not affect the spin?
     
  5. Oli

    Oli New Member

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    AFAIK it's a question of spin rate being greater from rifling than it could be from fins, and the fact that a large L/D (should be L : D, but if you write it correctly you get L:D!) penetrator, if spun, ends up with what is known in the aviation business as "roll-coupling" where the spin makes the thing want to go end-over end rather than round and round...

    Not sure about barrel wear, inasmuch as smooth bores tend to have a higher muzzle velocity, which would increase wear cf rifled, although there will be less due the rifling not being there to be worn down. But I've seen no figures (or even comments) on barrel wear factors, but I believe that EFC (Equivalent Full Charge) shot numbers are roughly the same.
     
  6. smeghead phpbb3

    smeghead phpbb3 New Member

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    i agree with Oli, rifled guns fire shells more accurately and longer rages, whereas smoothbore guns are ideal HEAT rounds because they do not cause them to spin. depends what type of ammo your tank is using i guess
     
  7. Grieg

    Grieg New Member

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    Oli didn't say that.

    Almost all gun designers (for MBTs) are going to smoothbore(or have already).
    I assume they have good reasons.
     
  8. Zhukov_2005

    Zhukov_2005 New Member

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    Another pro of the smoothbore gun is its ability to shoot guided missiles, such as the AT-8 fired from the T-80's 125mm gun. I'm not sure how effective this weapon system is (I've never read anything good about the Sheridan's 152mm gun/missle launcher, but that wasn't a great tank anyways), but it does provide that much more versatility.
     
  9. Hoosier phpbb3

    Hoosier phpbb3 New Member

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    Zhukov:
    The M151 Sheridan was not an MBT in the traditional sense, as it was designed as a "light" arborne-type tank and not as a true competitor to the M-60, Centurian, T-55/T-62-series MBT. It probably compares more favororably to the Soviet PT-76.
    The 152mm "Shillelagh" --at least as I understand it--was employed as a means to give this lightweight more punch if facing enemy MBTs.
    I remember when they were first deployed in Vietnam, and they had many problems with the Shillelagh weapons system. It was later fitted with a barrel "evacuator" to clear the barrel of unburned propellant between firings.
    There were incidents early-on in Vietnam in which American crews were injured or killed when a Shillelagh round was loaded into a hot, just fired barrel, and it cooked-off prematurely while the breech was still open.
    The Sheridan was also designed to "float" and had closed-cell foam in the hull under the armor. Being a "light-weight" as it were, it was often totally destroyed if it hit an anti-tank mine in Vietnam... unlike an M-48/M-60 which could be repaired.
    I've talked to a fellow that commanded an M-151, and my impression is that it was not real-popular with it's crews. He told of an incident where the "bustle" on the back of his tank literally fell-off and nearly killed him as he stood on the ground behind his tank. The welds had failed or some-such...

    Tim
     
  10. Zhukov_2005

    Zhukov_2005 New Member

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    Hoosier wrote:
    Sweet Lion of Zion, that must have been an absolutely atrocious situation.
     
  11. Oli

    Oli New Member

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    The Sheridan was a good idea badly executed. Apparently when firing Shilellagh (or Shillelagh, can never remember where the extra "L" goes :grin: ) the time of flight was so long against the targets it was designed for that the firing vehicle had to stay "turret up" long enogh for it to be destroyed before missile impact - bad! And when firing HE the short barrel gave such ferocious recoil that the entire crew had to hang on to something and the vehicle literally lifted the front end off the ground. And the recoil also apparently put internal equipment out of commision. Too much gun on too litle vehicle.
     
  12. liang

    liang New Member

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    The British are pretty stubborn about keeping rifled guns on their Challengers. But they are still pretty effective.
     
  13. Ricky

    Ricky New Member

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    [off topic - nice to see you again liang! :D ]
     
  14. liang

    liang New Member

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    Thanks Ricky, glad to see the forum is going stronger than ever.
     
  15. Blaster

    Blaster New Member

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    RE: Rifled vs smoothbore

    In the case of small-arms, rifling spins a bullet, making it more accurate than a smoothbore weapon. However, tank shells are so big and the rifling's so big that it doesn't really make a difference. So a 105mm rifled cannon and a 105mm smoothbore cannon will perform about the same.
    PS I got this stuff from an actual Canadian soldier, so if anyone disagrees...
     
  16. Gryle

    Gryle New Member

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    Blaster, spin stablisation is still the most effective method of stablising the vast majority of projectiles regardless of size. Small arms, long range artillery, all the way up to battleship guns all use it, those guns that don't use it are notable by their exception. Tank guns have started to use smoothbore barrels for several reasons, the extremely long, thin APDS type penetrators aren't well stablised by spining and pretty much require fins, a rotating HEAT charge's performance is degraded by rotation, and the breach and chamber have to be of stronger construction for a rifled gun as there is a pressure spike when the rifling first bites into the driving band.
     

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