Polygonal Rifling Velocity

This is a discussion on Polygonal Rifling Velocity within the Defensive Carry Guns forums, part of the Defensive Carry Discussions category; Lately I've been shooting a Kahr P40, which like the Glocks has polygonal rifling. The velocity seems to be noticeably higher than I expected and ...

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Thread: Polygonal Rifling Velocity

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    New Member Array Littlestone's Avatar
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    Polygonal Rifling Velocity

    Lately I've been shooting a Kahr P40, which like the Glocks has polygonal rifling. The velocity seems to be noticeably higher than I expected and I've heard this type rifling produces higher velocity. Does anyone have any experience with this? What have you noticed? Thanks much.

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    Member Array Ecucmgt's Avatar
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    How do you notice the velocity is higher.
    bmcgilvray likes this.

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    Ex Member Array Ram Rod's Avatar
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    Quote Originally Posted by Ecucmgt View Post
    How do you notice the velocity is higher.
    + Me too.

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    VIP Member Array Yoda's Avatar
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    Do you have some chronograph figures comparing a standard vs polygonal barrels of the same length using the same ammo?
    Yoda, I am, yes.

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    New Member Array Littlestone's Avatar
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    I'm chronographing the Kahr, but I've not done a head to head comparison with a firearm with non polygonal rifling. At this point it's just an impression based upon a fairly small number of examples. Not entirely sure it would be a valid comparison as there are so many other variables that could affect velocity. I think the only way to get a valid comparison would be to develop a fairly large database of comparison and then compare the aggragate averages. I could do that over time, but I thought I'd pose the question to the community first and see what others might know more authoritatively than me on the subject.

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    Senior Member Array mr surveyor's Avatar
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    it would be interesting to see a comparison between like models, equal barrel lengths, and the different rifling. The P40 with polygonal rifling and the CW40 with conventional rifling would be a perfect comparison.

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    Member Array kmagnuss's Avatar
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    Yes polygonal rifling supposedly yields higher velocities than standard types.

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    Quote Originally Posted by kmagnuss View Post
    Yes polygonal rifling supposedly yields higher velocities than standard types.
    True but, it's pretty much an irrelevant velocity increase.

    But, there are some other advantages to polygonal rifling.
    AKA less bullet deformation and extended barrel life....or at least a slightly more accurate barrel life for a slightly longer period of time.

    It is really tough to "wear out" or "shoot out" any handgun barrel. Your average shooter just couldn't wear out any high quality handgun barrel of decent hardness.
    Liberty Over Tyranny Μολὼν λαβέ

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    Quote Originally Posted by mr surveyor View Post
    it would be interesting to see a comparison between like models, equal barrel lengths, and the different rifling. The P40 with polygonal rifling and the CW40 with conventional rifling would be a perfect comparison.
    (credit to)
    ~~~> HadEmAll
    06-09-2011, 08:45 AM


    I chronographed several loads in the past with my previous K40 and current CW40 before I sold the K40.

    The CW40 with conventional rifling had higher velocity with all loads over the K40's polygonal rifling.

    UNFORTUNATELY... the CW40 barrel is also .1" longer. So in this case, the miniscule extra length appears to trump any velocity advantage of polygonal rifling.

    These are all 6 round averages:

    Winchester Ranger 155 grain JHP - K40=1168 fps --------- CW40=1175 fps
    Remington Express 155 grain JHP - K40=1127 fps --------- CW40=1149 fps
    Federal Classic 155 grain JHP - K40=1108 fps ------------- CW40 1117 fps

    The largest impact on muzzle energy was only around 18 pounds with the Remington

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