polygonal rifling

[sa champion]

what bad about this type of rifling? I've heard people say not to shoot lead in these barrels cause lead will build up causing excessive pressure and may Kaboom. Is that true? Was looking at a Khar 45 and man, it has a nice-smooth trigger but kinda long travel.

[dwtt]

The polygonal rifling, like on the glock barrels, don't have lands and grooves, but an octagonal shape. This octagon rotates as it proceeds down the barrel and stabilizes the bullet. Soft bullets like cast and copper coated bullets are just deformed by this type of rifling and don't get stabilized. There's no, or very little, angular momentum with a momentum vector parallel to the barrel's axis. (did I really say that? ) Since the bullets are being deformed more than in a regular barrel, there will be more lead ripped off the bullets as deposits in the barrel. If you get a gun with polygonal rifling, just shoot jacketed bullets and you'll be OK. The biggest problem with my glock barrel wasn't the leading, but the poor accuracy with coated and cast bullets. As for the barrel going Kaboom, I don't know if it will happen because I don't think anyone would put up with the poor accuracy for very long.

[Josh]

The polygonal rifling, like on the glock barrels, don't have lands and grooves, but an octagonal shape. This octagon rotates as it proceeds down the barrel and stabilizes the bullet. Soft bullets like cast and copper coated bullets are just deformed by this type of rifling and don't get stabilized. There's no, or very little, angular momentum with a momentum vector parallel to the barrel's axis. (did I really say that? ) Since the bullets are being deformed more than in a regular barrel, there will be more lead ripped off the bullets as deposits in the barrel. If you get a gun with polygonal rifling, just shoot jacketed bullets and you'll be OK. The biggest problem with my glock barrel wasn't the leading, but the poor accuracy with coated and cast bullets. As for the barrel going Kaboom, I don't know if it will happen because I don't think anyone would put up with the poor accuracy for very long.

Not true about the round deforming, they will shoot just fine and accurately as I have done this many times. The danger comes from the fact that the lead build up causes higher pressures. Its fine to shoot them as long as you remember to really clean the barrel out when youre done. Also the bullets are being deformed more or less the same as in a regular barrel.

"There's no, or very little, angular momentum with a momentum vector parallel to the barrel's axis"

English please?

[phish]

http://www.obermeyerbarrels.com/faq.html

http://www.zediker.com/books/rifleshooter/rs_technical.html

^click on thumbnail under Barrels

[PistolKidd]

The polygonal rifling, like on the glock barrels, don't have lands and grooves, but an octagonal shape. This octagon rotates as it proceeds down the barrel and stabilizes the bullet. Soft bullets like cast and copper coated bullets are just deformed by this type of rifling and don't get stabilized. There's no, or very little, angular momentum with a momentum vector parallel to the barrel's axis. (did I really say that? ) Since the bullets are being deformed more than in a regular barrel, there will be more lead ripped off the bullets as deposits in the barrel. If you get a gun with polygonal rifling, just shoot jacketed bullets and you'll be OK. The biggest problem with my glock barrel wasn't the leading, but the poor accuracy with coated and cast bullets. As for the barrel going Kaboom, I don't know if it will happen because I don't think anyone would put up with the poor accuracy for very long.

Polygonal rifling is very smooth and has more of a valley and hill type method for spinning the bullet.. if you've ever seen a glock barrel, it appears very smooth and has 'speed bump' type protrusions.. I dont know where dwtt is getting this 'octagonal' shape stuff.. but glock barrels DO NOT look like that.. there are no sharp angles inside the barrel..

The main reason they tell you not to shoot lead is because the buildup is much different than what you find in traditional barrels...Polygonal barrels seal teh bullet much better.. theres' no room for any excess lead to move..

the leading issue has to do with what Josh said.. You can get leading in the rifling that eventually increases the pressure OR you can get lead buildup in the throat area of the barrel..This can cause the round to not seat fully inside the chamber, allowing you to fire the gun OUT OF BATTERY.. which can cause a KABOOM type moment... In either case, both of these can contribute to a catastrophic failure in your gun..

Accuracy using lead in polygonal barrels is also fine...I've shot hundreds and hundreds of rounds a session wihtout cleaning through my brothers G17... No loss in accuracy.. Im not saying it was the 'brightest' thing to do.. but if I only had a 100 rounds of lead.. i wouldnt even blink twice about shooting it up in any of my glocks - except my G35..

Other companies like Steyr and HK use polygonal barreling on some of their firearms.. Just research the matter for yourself before you go and listen to people on the errornet..

Heres a start

http://www.glockfaq.com/reloading.htm

[saki302]

I don't call Glock barrels true polygonal rilfing. H&K barrels have the warped octagon shape- you can't see a clear separation between land and groove. The Glock barrels still show a clear separation, though the rifling is totally rounded out smooth at the edges. They do work the same though.

-Dave