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Thread: Glock's polygonal/hexagonal rifling

  1. #1
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    Glock's polygonal/hexagonal rifling

    Can anyone explain the differences btwn the polygonal rifling vs hexagonal rifling? On Glock's site under technology, they state that their polygonal rifling gives advantages, yet under the individual pistols the barrel rifling is referred to either right hand hexagonal or octagonal rifling. Why wouldn't they just call it polygonal or hexagonal if they're one and the same? I've heard it explained a number of different ways, like this, for example: The Gen 5 barrel is polygonal with grooves. The issue with polygonal barrels was that there weren't enough distinguishing marks to positively identify each bullet in a shooting to a particular gun. Look up "Glock Miami Barrel". Glock offers barrels wtih some traditional rifling grooves to law enforcement to help better identify each individual bullet when several officers are involved in the same shooting. Glock offered this barrel to the FBI for the same reason, and because of that they're including it in the Gen 5, which is a rebadged FBI M Glock."

    I don't believe the Gen 5 barrel is a lands and groove barrel as inferred in the explanation above, but it is an improved hexagonal barrel. I see that most people refer to Glock barrel rifling as polygonal rifling, but as I understand it, it really isn't a true polygonal rifling. It's a modified version of it. Hoping someone who has thorough knowledge of it can explain it to a non-engineer/technical type like me.
    Last edited by GCBHM; 09-23-2017 at 02:19 PM.

  2. #2
    Polygon: A geometric figure with multiple sides, number not specified.
    Hexagon: A geometric figure with six sides. Glock 9mm and .40 barrel interiors have six sides.
    Octagon: A geometric figure with eight sides. Glock .45 barrel interiors have eight sides.

    I tend to quibble with the terminology because I learned in sophomore geometry that a hexagon was a geometric figure with six STRAIGHT line segment sides, and there is no straight line to be seen inside a Glock barrel.
    But hey, the advertising department had to call it something.
    It is rather similar to 19th century Metford rifling, which the British abandoned because Cordite ate it up.

    I have not had a close look at a Gen 5 barrel and internet pictures are not helpful, it is hard to take a good picture of a long shiny hole.
    Code Name: JET STREAM

  3. #3
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    Quote Originally Posted by GCBHM View Post
    Can anyone explain the differences btwn the polygonal rifling vs hexagonal rifling? On Glock's site under technology, they state that their polygonal rifling gives advantages, yet under the individual pistols the barrel rifling is referred to either right hand hexagonal or octagonal rifling. Why wouldn't they just call it polygonal or hexagonal if they're one and the same? I've heard it explained a number of different ways, like this, for example: The Gen 5 barrel is polygonal with grooves. The issue with polygonal barrels was that there weren't enough distinguishing marks to positively identify each bullet in a shooting to a particular gun. Look up "Glock Miami Barrel". Glock offers barrels wtih some traditional rifling grooves to law enforcement to help better identify each individual bullet when several officers are involved in the same shooting. Glock offered this barrel to the FBI for the same reason, and because of that they're including it in the Gen 5, which is a rebadged FBI M Glock."

    I don't believe the Gen 5 barrel is a lands and groove barrel as inferred in the explanation above, but it is an improved hexagonal barrel. I see that most people refer to Glock barrel rifling as polygonal rifling, but as I understand it, it really isn't a true polygonal rifling. It's a modified version of it. Hoping someone who has thorough knowledge of it can explain it to a non-engineer/technical type like me.
    The M barrels are not Miami barrels. They are a hybrid barrel used to meet accuracy requirements in the RFI. Hybrid meaning it shares characteristics of both Glock polygon and conventional rifling.

    Some of those modifications appear to have been to the chamber and lead of the rifling, not just the rifling itself.

    Shorter lead / less freebore often helps accuracy.
    Last edited by HCM; 09-23-2017 at 10:51 PM.

  4. #4
    Quote Originally Posted by HCM View Post
    Shorter lead / less freebore often helps accuracy.
    It can affect ammo selection, there was one brand known for a short throat that simply would not chamber some of the heavy bullet loads.
    Drives reloaders nuts, there are a lot of rather blunt commodity bullets that have to be seated deep for such short throated barrels.

    I wonder how the "hybrid" barrel stacks up against SAAMI and CIP specs.
    Code Name: JET STREAM

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