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Rogue's post in the Glock thread about the potential changes for the upcoming "M" series Glocks raised a question for me on a subject to which I admit total ignorance. What is the practical difference between conventional rifling and Glock's polygonal rifling and why would one be more desirable than the other? | ||
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Fighting the good fight |
It's rumored that this was one of the considerations in going with conventional rifling on the 17M/19M: http://www.thefirearmblog.com/...miami-glock-barrels/ I've heard that the new conventional rifling might have been based on Glock "Miami rifling" as discussed in that article. It makes sense that the 17M/19M models, which at this time are limited to only LE agencies, would go with a type of conventional rifling that's more conducive than polygonal rifling to ballistic identification, for help in officer-involved shooting investigations in which more than one officer fires. Polygonal rifling is also less ideal when shooting unjacketed lead bullets, as it fouls more easily. But I doubt if that factored into Glock's decision. | |||
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| You're going to feel a little pressure... |
I believe polygonal rifling creates a better gas seal, based on the very slightly higher velocities Glock barrels will produce, inch for inch. I don't know of any other advantages? Production cost/ease? Bruce "The designer of the gun had clearly not been instructed to beat about the bush. 'Make it evil,' he'd been told. 'Make it totally clear that this gun has a right end and a wrong end. Make it totally clear to anyone standing at the wrong end that things are going badly for them. If that means sticking all sort of spikes and prongs and blackened bits all over it then so be it. This is not a gun for hanging over the fireplace or sticking in the umbrella stand, it is a gun for going out and making people miserable with." -Douglas Adams “It is just as difficult and dangerous to try to free a people that wants to remain servile as it is to try to enslave a people that wants to remain free." -Niccolo Machiavelli The trouble with fighting for human freedom is that one spends most of one's time defending scoundrels. For it is against scoundrels that oppressive laws are first aimed, and oppression must be stopped at the beginning if it is to be stopped at all. -Mencken | |||
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| Fighting the good fight |
Polygonal rifling supposedly results in longer barrel life, but I don't know if that's verified fact or just rumor. | |||
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| A teetotaling beer aficionado  |
Polygonal barrels are hammer forged. The equipment to do this is said to be very expensive, and then there is a precise heat treat process needed to relieve the internal stress caused by the cold hammer process. So the manufacturer would need pretty large production quantities to get a payback on the machining equipment and heat treat process. Sounds like Glock and HK to me. Men fight for liberty and win it with hard knocks. Their children, brought up easy, let it slip away again, poor fools. And their grandchildren are once more slaves. -D.H. Lawrence | |||
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| Member |
I suspect that the main advantage of the so-called* "polygonal" rifling is that the hammer forge mandrel without sharp corners will last longer in mass production. *My sophomore geometry teacher defined a Polygon as a closed figure made up of STRAIGHT line segments. Not seen in gun barrels so described. | |||
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