What is the point of Glock polygonal rifling?

There are a number of rifling methods. Drill and cut the grooves, drill and pull a carbide forming tool through the barrel [button rifled ], cold forge the barrel over a polygonal mandrel. The last one has been used for over 40 years !! A typical rifle barrel starts out as a 12" tube ,hammered over a mandrel and ends up as a 24" poly rifled barrel !. :)
 
Several things

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Dot in the five sided symbol is +p+ not all glock barrels are.

Not all Glocks are hexagonal rifled. In fact, only about 80% are. Out of my all factory Glocks, two of them are hexagonal.

Prudent is not something adults teach kids in the last couple of generations. Example, it can be done, but it is best NOT to pee into a strong wind. Another example of head strong, but not from knowledge is shooting lead bullets from any gun that says not to in the owners manual.

Another example is lighting fires with gasoline as kindling. It can be done, but it is not prudent to do so. Why? The thousands of people that have tried lighting a fire this way , some of them learned it was dangerous. Other people seeing it is danderous, eithor dont do it, prudent, or do it anyway and just try to be a bit more careful.

John Wayne had a saying he was fond of: "Life is hard, it is harder if you are stupid".

Glock lead shooters will learn from the expirence of others or they will learn from their own experiences. One involves reading, watching you tube videos, the other way involves bandages and eating crow.

Their was a billionaires kid some years ago, liked to go down the amazon river on small boats and study tribsmen known to be waring and cannibals. He went in and out of the jungle many times with no problems, until the time he did not come out of the jungle.

Prudent. Build it into your lifestyle and amaze your friends and family.
 
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Please show pictures and particulars of FACTORY Glock barrels not like the usual rounded "polygon" cross section.


Yes, there are other rifling methods. Those big Krupp, etc. hammer forges are expensive.
There are several high end shops doing cut rifling mostly for target shooters or to produce low demand rifling plans.
Douglas and Hart are well known button rifling shops.
I assume S&W still broach cuts standard barrels, as does Pedersoli.

The monster magnum Smiths are ECM rifled, as are Nowlin 1911 barrels.

Springfield Armory used scrape rifling on 1903 Match and Sporter barrels. A similar setup to cut rifling, but the cutter was different and took out less metal per pass. A lot of passes, but a smooth and precise barrel.
 
From Spare mag:

Uhhh...just what IS polygonal rifling? How is it different than conventional rifling?
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There is a good deal of information on this available some links to that are below.

The central reason Glock and some others use polygonal rifling is that it can reduce costs of production.

Below is some tests on velocity conducted by "Ballistics by the inch" on different type barrels, polygonal versus traditional, with different loads. To see if there is a real world difference.

http://www.ballisticsbytheinch.com/rifling.html

There is a small but noticeable increase in velocity with polygonal rifling with jacketed bullets in general. This will vary some by gun and load.

http://en.wikipedia.org/wiki/Polygonal_rifling

Google polygonal rifling and there are many explanations and examples.

tipoc
 
Dot in the five sided symbol is +p+ not all glock barrels are.
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Based on excerpts from vintage Glock armorers manuals in combination with a survey of a few older 9mm Glocks, there are definitely some 9mm Glocks out there which are rated for ammunition with higher pressure than +P and which have the pentagon without the dot stamped on the barrel.

In the oldest Glock armorers manuals, they published the pressure specifications for the 9mm Glocks. Those figures are well into the +p+ pressure range and yet it's not hard to find 9mm Glocks from that era which do not have the pentagon dot marking.

There is some information out there that suggests that the pentagon and the pentagon with the dot relate to the grade of steel used in the barrels and possibly chamber support but I have not been able to confirm that definitively.
Not all Glocks are poligonal rifled. In fact, onlt about 80% are. Out of my all factory Glocks, two of them are not poligonal.
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I can tell you with 100% certainty that all Glock barrels have polygonal rifling. If you have Glocks with barrels that actually don't have polygonal rifling then the barrels are aftermarket barrels.

Trying to look down the bores and assess the rifling type that way can be tricky with Glock barrels. There are two ways which are fairly accurate. Look ONLY at the crown of the barrel where the rifling meets the muzzle and it's usually easy to verify that the lands have rounded tops instead of the typical square tops. The most accurate way is to fire a round through the bore into soft material or slug the bore and look at the resulting shape of the bullet.

There are differences in the number of "lands and grooves" in the various Glock barrels but they are all polygonal.
 
In my old age I got my shoelaces tied together again

Polygonal multi sides
Hexagonal 6
Octoganal 8

My old brain switched meanings of poly and hex.
 
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My statment was a correct one, as Glock uses hexagonal rifling on the big boys.
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You are correct that hexagonal rifling is used on some barrels. However, it is incorrect to imply that hexagonal rifling is not polygonal rifling.

Glock uses octagonal and hexagonal rifling on their barrels. Hexagonal and octagonal rifling are two variants of polygonal rifling. The difference is how many "lands and grooves" are present--or how many sides the polygon in question has, if you prefer.
 
I don't know what you call a "big boy" in the Glock lineup, but their largest caliber is .45 ACP and GAP, which use octogonal (their spelling) rifling, not hexagonal, which is limited to .40 and down.

And you might want to check the dictionary definition and spelling of polygonal, too.

It is all made up advertising drivel anyhow.
Going back to sophomore geometry, I recall that a polygon (hexagon, octagon) is a figure bounded by STRAIGHT line segments. The washed out swoops and swishes of Glock etc. barrel cross sections do not qualify.
I don't care what Wiki, says; if they can't tell the difference between the true hexagonal bore of a Whitworth and the rounded lands and grooves of a Metford (or Glock), they are beneath my notice.
 
It may be as Jim says that the origin of the term "polygonal rifling" has more to do with marketing than proper English or geometric accuracy but it is, these days, a widely used and accepted term for the results of hammer forged barrels.

I'm not sure what the Germans called it when they developed it during WWII to save time and costs in barrel production. I'll have to crack a book and see.

Meanwhile a couple of other sources of information which I hope are not beneath people's notice.

http://www.firearmsid.com/A_bulletIDrifling.htm

http://humanevents.com/2010/06/08/barrels-and-bullets-conventional-versus-polygonal-rifling/

And with rifles...

http://precisionrifle.files.wordpre...ifling-from-david-tubbs-the-rifle-shooter.pdf

And a bit on the Whitworth rifling...

http://firearmshistory.blogspot.com/2010/05/rifling-polygonal-bore-and-whitworth.html

tipoc
 
So now my next basic question...how are barrels made?

Do you take metal stock, roll the stock into a cylinder and then drill out the center? Seems very time consuming. But if you roll stock around a mold or template of some type, then you essentially weld the barrel rogether, which has problems too....

.????

Then how do you cut in the rifling, regardless of type?
 
Simply put:

Take a donut of steel and forge it around a mandrel.

Bore a hole in a block of steel, then rifle it through several methods.

Cast it to shape, then rifle.
 
Glock barrels are cold hammer forged.

The barrel stock is drilled with an over-sized hole and placed on a properly shaped mandrel. Then hammers strike the outside of the barrel stock and shape it to the mandrel. Multiple hammers strike the barrel stock simultaneously and the barrel stock and mandrel rotate together slowly as they pass through the hammers.

http://youtu.be/lHKdDutha8k

http://youtu.be/yCF2Gd_oCMM
 
Has anybody taken the next step and resurrected the Lancaster Oval Bore? There is no way to beat it as to gas seal and easy cleaning. ECM or hammer forge could probably do it economically.
It would take rocket science and some prototypes, googling around indicates that some period Lancasters were accurate, some not; and the differences not then obvious.
 
So now my next basic question...how are barrels made?
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Some links were posted earlier which explained the different processes and showed them. You can click on those or use google. You tube has videos of the different processes.

Basically, today, broached, button made or hammer forged.

tipoc
 
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