AR-15 Polygonal Rifling
I'm looking at a new upper for my AR and one of the ones I've looked at says it has 3 groove polygonal rifling. It has an 18" barrel with 1/8 twist.
Is the polygonal rifling a good thing, a bad thing, or a marketing gimmmick?
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=249826520
Kinda figured it for a gimmick but thought I'd check..
Is the polygonal rifling a good thing, a bad thing, or a marketing gimmmick?
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=249826520
Kinda figured it for a gimmick but thought I'd check..
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in my OPINION.., GIMMICK 0 -
Why isn't everyone using them?
CP
Ed
The vast majority of barrels are hammerforged.
But not polygonal.
CP0 -
quote:Originally posted by cpermd
Why isn't everyone using them?
CP
Did HK have a patent on the poly rifling?0 -
quote:Originally posted by cpermd
Why isn't everyone using them?
CP
Because as a general rule, it must be hammer forged. Hammer forged barrels of good quality are way more expensive than cut, or button rifled barrels of the same quality.
Best0 -
" Groove " and " Polygonal " don't fit the same bore for me.
Polygonal bores are polygons, i.e. octogon, hexagon, pentagon, in shape, and they are 'twisted' to impart rotation.
Hammer forging, while expensive, seems a good method for polygonal rifling. Cutting, obviously does not come first to my mind.
'THREE GROOVE' uh, Triangular ?---sounds unlikely.
Tuneup Please.0 -
quote:Originally posted by cpermd
Why isn't everyone using them?
Just because these barrels are relatively uncommon in longarms, by itself doesn't mean that polygonal rifling is either a good or a bad idea.
Glock, H&K, CZ, and Kahr arms all use polygonal rifling in some or all of their pistol barrels.
The advantages of polygonal rifling vs non-polygonal include higher velocities with the same ammo, potentially easier to clean, and longer barrel life.
Disadvantages include potentially greater cost, and possible restrictions on using non-jacketed bullets (since these barrels lead up faster and it can be harder to scrub out the lead). Greater cost is because the polygonal barrels have to be hammer-forged, rather than cut.
For what its worth, Noveske uses polygonal rifling on its ARs, and I don't think anyone thinks those guns are "junk".
Personally, I'm agnostic on polygonal rifling for an AR barrel. I don't have any experience with them, and I can't honestly say whether or not they really perform better. I don't think I'd be willing to pay much more money for one, though.0 -
NeoBlackdog,
Polygonal rifling dates back to the mid-1850's so it is most certainly NOT a gimmick. The French were among the first pioneers but followed closely by the Germans and finally the Americans with similar polygonal barrel patterns used for small cannons and howitzers. The Japanese used polygonal rifling in their Arisaka rifles.
"The term "polygonal rifling" is fairly general, and different manufacturers employ varying polygonal rifling profiles. H&K, CZ and Glock use a female type of polygonal rifling. This type has a smaller bore area than the male type of polygonal rifling designed and used by Lothar Walther (GER/USA). Other companies such as Noveske (Pac Nor) and LWRC use a rifling more like the conventional rifling with both of the lands sides being sloped but has a flat top and defined corners, this type of rifling is more of a canted land type of rifling than polygonal rifling. Then there is the 5R rifling which is a polygonal form because of the canted sides of the lands but also includes rounded corners in the bottom of the grooves."
The current crop of polygonal and 5R rifled barrels represents the new height of barrel manufacturing and accuracy. First and foremost, they are created by both button rifling and cut-rifling methods. This eliminates the hammer forged barrels with their abundance of inherit stresses built into each barrel. Manufacturers using the polygonal/5R rifling are the top barrel makers in the US today, including but not limited to:
Bartlein
Schneider
Krieger
Broughton
Lothar Walther
Shilen
and probably a dozen more...
A quick check of the barrel column from most of the national shooting competitions will give you a far better idea of the abundant use of polygonal rifled barrels.
Best.0 -
quote:Originally posted by nononsense
NeoBlackdog,
Polygonal rifling dates back to the mid-1850's so it is most certainly NOT a gimmick. The French were among the first pioneers but followed closely by the Germans and finally the Americans with similar polygonal barrel patterns used for small cannons and howitzers. The Japanese used polygonal rifling in their Arisaka rifles.
"The term "polygonal rifling" is fairly general, and different manufacturers employ varying polygonal rifling profiles. H&K, CZ and Glock use a female type of polygonal rifling. This type has a smaller bore area than the male type of polygonal rifling designed and used by Lothar Walther (GER/USA). Other companies such as Noveske (Pac Nor) and LWRC use a rifling more like the conventional rifling with both of the lands sides being sloped but has a flat top and defined corners, this type of rifling is more of a canted land type of rifling than polygonal rifling. Then there is the 5R rifling which is a polygonal form because of the canted sides of the lands but also includes rounded corners in the bottom of the grooves."
The current crop of polygonal and 5R rifled barrels represents the new height of barrel manufacturing and accuracy. First and foremost, they are created by both button rifling and cut-rifling methods. This eliminates the hammer forged barrels with their abundance of inherit stresses built into each barrel. Manufacturers using the polygonal/5R rifling are the top barrel makers in the US today, including but not limited to:
Bartlein
Schneider
Krieger
Broughton
Lothar Walther
Shilen
and probably a dozen more...
A quick check of the barrel column from most of the national shooting competitions will give you a far better idea of the abundant use of polygonal rifled barrels.
Best.
Thanks! What do you think of the upper that is listed above? I'm wanting something to throw up to 77 grain bullets with good accuracy. I already have a 16" 1/9 that is great with the 55 grain bullets but would like an upper that can easily handle the heavier bullets. I will likely use the rifle in local Sporting Highpower matches and for cougar hunting.0 -
NeoBlackdog,
I think the parts it's assemble from are O.K. except that the cheese grater hand guards always give me pause. I know that they're all the rage but make sure that it will go along with your handling during your course of fire. The 1:8" twist will handle the 77 grain bullets just fine.
Keep in touch with us if you decide to get this. We'd all enjoy a good product review and accuracy testing.
Best.0 -
Wow. The diagram of the Black Hole 3-groove "polygonal" looks like a Lancaster oval bore with one lobe added. They carefully don't give dimensions.
I have no information on the Black Hole barrel, but anything that spins up the bullet without deforming it unevenly will probably shoot OK. As witness all the different brands and types Nonsense lists.
All of the barrel makers these days would flunk my highschool geometry class, where a polygon was defined as
1: a closed plane figure bounded by straight lines
These melted looking things shown in gun advertising do not qualify.0 -
If I wanted an upper with polygonal rifling I would just buy a Noveske and be done with it. Yes, it will cost more, but at least I would know I am purchasing from a very reputable company with a track record of producing very accurate production rifles. 0
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