[Samari Jack]

I just read this "Polygonal rifling is currently seen on pistols from CZ, Heckler & Koch, Glock, Tanfoglio, and Kahr Arms, as well as the Desert Eagle."

Expands on the use of lead issue.:what:

[bds]

I do not consider Glock rifling as true "polygonal". Unlike true polygonal barrel shape that rotates down the barrel (picture on the right), Glock barrels are round with six (hexagonal) rounded hill/valley rifling down the barrel (picture in the middle).

Traditional land/groove rifled barrel in the middle and true polygonal barrel on the right - http://en.wikipedia.org/wiki/Gun_barrel
http://upload.wikimedia.org/wikipedia/commons/thumb/1/12/Gun_barrels_cross_sectional_drawing.png/799px-Gun_barrels_cross_sectional_drawing.png

[jfrey]

Glock, Kahr, and Walther claim the polygonal rifling is more accurate, but at normal SD ranges, who is gonna know? I've never noticed any significant improvement in accuracy at normal pistol ranges.

[twofifty]

Wasn't there a 'poly-something or other' artillery gun made during the civil war?

iirc, they called the projectile a 'bolt', and it was twisted to the same rifling as the barrel.

[bds]

Polygonal rifling were designed to reduce high pressure gas leakage through the voids between the bullet and the land/groove rifling of conventional barrels - http://en.wikipedia.org/wiki/Polygonal_rifling

http://upload.wikimedia.org/wikipedia/commons/thumb/3/3b/Polygonal_vs_normal_rifling.svg/493px-Polygonal_vs_normal_rifling.svg.png

IIRC, when Glock was introduced initially, they claimed the smoother "rounded" rifling allowed tighter jacketed bullet-to-barrel seal and leaked less high pressure gas which resulted in higher muzzle velocities (I think comparative velocities were higher out of Glock barrels). Still, I do not believe Glock barrels have polygonal rifling, just rounded land/groove rifling that's smoother (see comparison pictures below).


Lone Wolf barrel with traditional square cut land/groove rifling:
http://www.thehighroad.org/attachment.php?attachmentid=162419&stc=1&d=1333939386

Glock barrel with rounded rifling:
http://www.thehighroad.org/attachment.php?attachmentid=151381&stc=1&d=1319341855

[Nick93]

Glock have polygonal rifling but they differ in the type of polygon depending on the number of valleys and hills ... the Hk has an octagonal barrel and the glocks have an hexagonal barrel with the exception of the .45 acp that have the same as the HK

The octagonal also have some sort of "rounded hills" but its much smaller since they have 8 to cover the diameter of the bore... If you look at the muzzle from the chamber you can see a polygon in either barrel.

Hope this helps :)

[kelbro]

If your question is can they shoot lead, then I will answer 'yes' my HKs shoot lead just fine.

[bds]

Glock have polygonal rifling ... Hk has an octagonal barrel ... If you look at the muzzle from the chamber you can see a polygon in either barrel.
I beg to differ. If you look at Glock barrels from either ends, you definitely see a ROUND barrel with distinct rifling and not a HEXAGON.

Here's a better picture of Glock barrel from both ends

http://www.thehighroad.org/attachment.php?attachmentid=163255&stc=1&d=1335152658

[Jim Watson]

The term polygonal is rather loosely used by barrel makers these days and I'm not going to get into fine definitions.

"Wasn't there a 'poly-something or other' artillery gun made during the civil war?

iirc, they called the projectile a 'bolt', and it was twisted to the same rifling as the barrel."


Yes, that was the Whitworth true hexagonal bore field piece. There were also .451 rifles on the plan, famed in song and story as "Confederate Snipers." What is less known is that the Whitworth hex bore (and the pentagonal and heptagonal bores cut by companies intent on cashing in on the gimmick without running into patent lawsuits) was obsolete within about five years. The land and groove Gibbs, Metford, and Rigby rifing took over for the remainder of the muzzleloading bullet firing rifle era. I believe it was the Rigby that Remington and Sharps breechloaders beat at Creedmoor in 1876.

[Rule3]

A polygon is a "many sided" shape, a hexagon is a six sided polygon:D

There are many "polygons" all with different amount of edges.

[Odd Job]

Those are great pictures of the rifling, bds.

[bds]

Thanks. Took like 30 tries to get the focal length just right.

[Odd Job]

Yep, I tried to get pics of my Vektor rifling and didn't do so well (it's a bit more difficult because the barrel is fixed to the frame) so I know it is no easy deal. In fact not easy even if the barrel comes out...