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Posted: 7/22/2021 8:04:01 AM EDT
[#1]
They used to be more common than they are now; for example, the Martini-Henry uses a form of polygonal rifling.
I suspect it just doesn't stand up well to the increased pressure of smokeless rifle rounds. The Brits had this issue with the Lee-Metford rifles (which used the same sort of rifling the Martinis had) and Cordite .303; it shortened barrel life dramatically. |
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Posted: 7/22/2021 8:05:45 AM EDT
[#2]
If it improved accuracy, the match guys would be using it.
They don't, so I suspect it doesn't. |
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Posted: 7/22/2021 8:23:20 AM EDT
[#3]
HK rifles also used it.
There were some AR barrels for awhile. They were accurate. Easier to ,do, button cut rifling,,or "hammer forged". Polygon ses harder,or rather fewer barrel manufacturers do it. They can be found. https://vtsupply-com.3dcartstores.com/Black-Hole-16-556-M4-Carbine-750-1-8-Polygonal-Rifling-Barrel_p_1261.html https://columbiariverarms.com/rifiling-manufacturing-process/ |
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Posted: 7/22/2021 8:24:42 AM EDT
[#4]
Remington's famous 5R rifling was a form of polygonal rifling, and polygonal rifling is simply a more difficult and expensive process than conventional rifling, and it is less well-known here.
It's a lot like gain-twist rifling... some people notice benefits, some don't. Bartlein does gain-twist, and has great success with it. Black Hole Weaponry barrels were/are polygonally-rifled, and they are well-known for superior accuracy with match shooters. It's a lot like brand loyalty.... not everyone is willing to honestly try different things. I have both conventionally-rifled and polygonally-rifled barrels which are match-quality. I do find the polygonally-rifled barrels to be a bit more consistent, especially in high round-count circumstances (they don't retain fouling to the same degree as conventional barrels). |
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Posted: 7/22/2021 8:27:20 AM EDT
[#5]
Is Black Hole Weaponry still around?
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Posted: 7/22/2021 8:28:46 AM EDT
[#6]
Quote HistoryQuoted: Is Black Hole Weaponry still around? |
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Posted: 7/22/2021 8:28:46 AM EDT
[#7]
Quote HistoryQuoted: If it improved accuracy, the match guys would be using it. They don't, so I suspect it doesn't. Yep. Look at what the guys who win titles use. If it helped they’d be using it. |
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Posted: 7/22/2021 8:43:56 AM EDT
[#8]
Triarc uses polygonal rifling in their Track 2.0 barrels. I just got an 11.5 one and tested it out yesterday. M855 was not great from it, but M193 did well. I did see some tests of theirs that seemed to give the edge to heavier bullets. I used AE and IMI, seemed to work. Using a TA31f on it, not using it for precision. It was an in stock barrel instead of a 6 month wait for a Criterion Core so giving it a go.
Triarc Systems 11.5 |
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Posted: 7/22/2021 8:45:42 AM EDT
[#9]
I had one in a wylde clambering. After 1400 rounds it was keyholing!
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Posted: 7/22/2021 9:02:58 AM EDT
[#10]
I have a polygonal LW barrel and I think my Larue Stealth barrel is polygonal.
They're not the most accurate barrels I own. The LT might be the best value barrel I own since they were relatively inexpensive for a period of time. I think the most important thing regarding barrel quality is that it's made in WI by the Obermeyer Industrial Complex 
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Posted: 7/22/2021 9:09:27 AM EDT
[#11]
Quoted: I always read that it gives a slight accuracy edge over traditional rifling (in pistols anyways).... It doesn't improve accuracy. It provides a sight increase in velocity because the bullet makes a better seal in the barrel. |
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Posted: 7/22/2021 9:14:47 AM EDT
[#12]
Quote HistoryQuoted: I had one in a wylde clambering. After 1400 rounds it was keyholing! It happens. Higher velocity and a wider range of bullet lengths can lead to issues with polygonal rifling. Plus the cost savings in manufacture only seems to show up with short - as in pistol length - barrels. |
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Posted: 7/22/2021 9:15:33 AM EDT
[#13]
Quote HistoryQuoted: Is Black Hole Weaponry still around? Yeah, but operating under their parent-company Columbia River Arms. Same people from what I understand. Barrels are still marked with the BHW logo. |
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Posted: 7/22/2021 9:19:12 AM EDT
[#14]
Noveske
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Posted: 7/22/2021 9:24:07 AM EDT
[#15]
Quote HistoryQuoted: It happens. Higher velocity and a wider range of bullet lengths can lead to issues with polygonal rifling. Plus the cost savings in manufacture only seems to show up with short - as in pistol length - barrels. Quote HistoryQuoted: Quoted: I had one in a wylde clambering. After 1400 rounds it was keyholing! It happens. Higher velocity and a wider range of bullet lengths can lead to issues with polygonal rifling. Plus the cost savings in manufacture only seems to show up with short - as in pistol length - barrels. Great, never knew this, just got it, guess I'll have to keep an eye out on it. |
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Posted: 7/22/2021 9:26:00 AM EDT
[#16]
Arisakas had Metford rifling, and many had a chrome-lined bore as well.
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Posted: 7/22/2021 10:47:52 AM EDT
[#17]
Quote HistoryQuoted: Noveske Not really. They have “ratchet rifling” that’s more like a traditional groove with the edges knocked off asymmetrically. |
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Posted: 7/22/2021 10:51:03 AM EDT
[#18]
Quote HistoryQuoted: Remington's famous 5R rifling was a form of polygonal rifling, and polygonal rifling is simply a more difficult and expensive process than conventional rifling, and it is less well-known here. Remington is more like traditional rifling with grooves that aren’t cut at 90 degrees. |
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Posted: 7/22/2021 10:51:31 AM EDT
[#19]
Quote HistoryQuoted: Great, never knew this, just got it, guess I'll have to keep an eye out on it. Quote HistoryQuoted: Quoted: Quoted: I had one in a wylde clambering. After 1400 rounds it was keyholing! It happens. Higher velocity and a wider range of bullet lengths can lead to issues with polygonal rifling. Plus the cost savings in manufacture only seems to show up with short - as in pistol length - barrels. Great, never knew this, just got it, guess I'll have to keep an eye out on it. It's not a huge problem. Just don't stray from the "standard" length (in terms of the actual contact surface of the bullet) projectile for the caliber. |
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Posted: 7/22/2021 12:07:17 PM EDT
[#20]
Based off the replies, it kinda seems like it is hit or miss with the barrels.
Seems like they are either loved, or they had issues. |
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Posted: 7/22/2021 12:28:35 PM EDT
[#21]
Quote HistoryQuoted: Based off the replies, it kinda seems like it is hit or miss with the barrels. Seems like they are either loved, or they had issues. It boils down to manufacturing cost - polygonal rifling is hammer forged/formed over a mandrel, which is great for mass production. If you aren't producing enough to take advantage of the economies of scale, it becomes less attractive as a fabrication method since there are no distinct performance gains to offset your costs. I haven't tried it on my machines, but I bet I could make an extremely accurate (dimensionally) rifled pistol barrel with a CNC turning center, saving the investment in tooling and machinery costs associated with forging polygonal barrels. |
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Posted: 7/22/2021 12:54:43 PM EDT
[#22]
Not an expert, but I think it is cost, and productivity, ie how many they make per hour.
The old site sponsor, the now defunct Olympic Arms used to have 2 riflings for their AR guns, button and cut. According to the guy I forget his name now, to make a button riffling that have a carbide broach that they shove down a drilled barrel under tremendous hydraulic pressure, one pass and ta da! one 1/9 barrel. Cut rifling requires multiple passes. Their production SUM barrels were shooting 0.5" shot groups at 100yds. ETA: SUM=stainless steel ultra match |
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Posted: 7/22/2021 1:26:58 PM EDT
[#23]
Not an expert but the cost of a rifling machine vs the initial purchase of a hammer forging machine are probably similar but as someone mentioned, you can turn out hammer forged barrels by the thousands very quickly.
Hammer forging has several drawbacks It creates a great amount of stress in the steel causing warping after a few rounds are fired which is the main reason why its not used for rifles very much. I read that the Steyr SSG sniper rifle used hammer forged barrel that were pressed into the receiver. It did not have a reputation for great accuracy after heating up. Cut rifling is still the least stressful way to cut rifling and is also the most expensive due to the labor/time involved. Also make the most accurate barrels. Canada(Diemaco) used to hammer forge their C7 barrels not sure if they still do. |
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Posted: 7/22/2021 1:30:53 PM EDT
[#24]
 Exhibit A |
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Posted: 7/22/2021 1:42:07 PM EDT
[#25]
Quote HistoryQuoted: Not really. They have “ratchet rifling” that’s more like a traditional groove with the edges knocked off asymmetrically. Pepperidge Farm remembers when Noveske only used Pac-Nor toobs. |
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Posted: 7/22/2021 1:51:52 PM EDT
[#26]
Quote HistoryQuoted: Noveske I have an 18" SPR barrel, they used 5R rifling in their stainless barrels, not true polygonal rifling. This is from Faxon but the concept is the same in Noveske barrels: 5R has lands opposite grooves, and the angle at the top of the land isn't as sharp as a conventional barrel:  This is polygonal rifling: 
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Posted: 7/22/2021 1:58:13 PM EDT
[#27]
Quote HistoryQuoted: Not an expert, but I think it is cost, and productivity, ie how many they make per hour. The old site sponsor, the now defunct Olympic Arms used to have 2 riflings for their AR guns, button and cut. According to the guy I forget his name now, to make a button riffling that have a carbide broach that they shove down a drilled barrel under tremendous hydraulic pressure, one pass and ta da! one 1/9 barrel. Cut rifling requires multiple passes. Their production SUM barrels were shooting 0.5" shot groups at 100yds. ETA: SUM=stainless steel ultra match Olympic broached barrels. Think of it as multi point cut rifling that is done similarly to the button rifling process. |
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Posted: 7/22/2021 11:17:23 PM EDT
[#28]
Quote HistoryQuoted: I have an 18" SPR barrel, they used 5R rifling in their stainless barrels, not true polygonal rifling. This is from Faxon but the concept is the same in Noveske barrels: 5R has lands opposite grooves, and the angle at the top of the land isn't as sharp as a conventional barrel: https://faxonfirearms.com/product_images/uploaded_images/riflingprofiles-zps0f29dd06.jpg This is polygonal rifling: http://www.sturmgewehr.com/bhinton/Heckler_Koch/PolygonalStandardRifling.jpg Quote HistoryQuoted: Quoted: Noveske I have an 18" SPR barrel, they used 5R rifling in their stainless barrels, not true polygonal rifling. This is from Faxon but the concept is the same in Noveske barrels: 5R has lands opposite grooves, and the angle at the top of the land isn't as sharp as a conventional barrel: https://faxonfirearms.com/product_images/uploaded_images/riflingprofiles-zps0f29dd06.jpg This is polygonal rifling: http://www.sturmgewehr.com/bhinton/Heckler_Koch/PolygonalStandardRifling.jpg Cool, I never knew what 5R was... |
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Posted: 7/23/2021 7:50:52 AM EDT
[#29]
Quote HistoryQuoted: It boils down to manufacturing cost - polygonal rifling is hammer forged/formed over a mandrel, which is great for mass production. If you aren't producing enough to take advantage of the economies of scale, it becomes less attractive as a fabrication method since there are no distinct performance gains to offset your costs. I haven't tried it on my machines, but I bet I could make an extremely accurate (dimensionally) rifled pistol barrel with a CNC turning center, saving the investment in tooling and machinery costs associated with forging polygonal barrels. Not all poly rifling is hammer forged. Black hole weaponry is button rifled polygonal. https://columbiariverarms.com/rifiling-manufacturing-process/ While it does not specifically say button in that link, it does not say hammer forged either. I then found a thread on another forum where someone from the company posted about their barrels and someone asked if it was hammer or button. They said button. http://www.predatormastersforums.com/forums/ubbthreads.php?ubb=showflat&Number=1610592 |
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Posted: 7/23/2021 9:54:45 AM EDT
[#30]
Quote HistoryQuoted: Not all poly rifling is hammer forged. Black hole weaponry is button rifled polygonal. https://columbiariverarms.com/rifiling-manufacturing-process/ While it does not specifically say button in that link, it does not say hammer forged either. I then found a thread on another forum where someone from the company posted about their barrels and someone asked if it was hammer or button. They said button. http://www.predatormastersforums.com/forums/ubbthreads.php?ubb=showflat&Number=1610592 True enough, but judging from the comments here regarding performance, and lack of popularity over other forms of rifling, there doesn't appear to be any advantage (other than manufacturing by forging) to using it. From a manufacturing standpoint, broaching with a button die has its own issues, but is better suited to short-run or one-off production than hammer forging is. Also, I assume that the machinery to produce it is more readily available. |
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