Polygonal - What's The Point?

[Bill K]

So, reading here and on a number of other gun forums there seems to me a consensus that polygonal "rifling" doesn't amount to a dimes worth of difference in a handgun shot @ SD distances. Yet Kahr, Glock and several other manufactures offer handguns with or come standard with polygonal barrels. So what is the point? Why do they even bother?

Thanks,
Bill K.

[jocko]

I think prestige of a top quality barrel but ur rigfht at SD distance, proably no rifleing will suffice. the TRaurus Judge has oh so slight rifling in it just enough to quality it as a rifle barrel but it seems to shoot 45 long colts OK. that gun was meant to shoot shotshells and nothing else but to get around the law, they had to rifle that barrel, ..

[Bawanna]

Polygonal rifling (pronounced /pəˈlɪɡənəl/, US dict: pə·lĭg′·ə·nəl) is a type of gun barrel rifling wherein the traditional lands and grooves are replaced by "hills and valleys" in a rounded polygonal pattern, usually a hexagon or octagon.

Polygons with a larger number of edges provide a better gas seal in relatively large diameter polygonally rifled bores. In the Glock pistol, for instance, octagonal rifling is used in the large diameter .45 ACP bore, which has a 11.23 mm (0.442 in) diameter, since it resembles a circle more closely than the hexagonal rifling used in smaller diameter bores.

[Bawanna]

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

This link relates alot of the history, pros and cons to polygonal rifling. Some good information there to start with.

[ripley16]

Lasts longer, easier to clean, and some produce higher velocity... all good things.

[jocko]

I've got 31000+ rounds to prove longer lasting and easier to clean.in my trusty PM9, so u-all put that in ur pipe and smoke it!!

[Willieboy]

Golly Bawanna, you're quite cerebral this evening.

[kpm9]

Forensically, it is apparently harder to get a match from a bullet that traveled through a polygonal bore, than one that traveled through a rifled bore with std land and grooves.

Believe it, or don't.

[CJB]

I'm not convinced on the wear claim, for the following reason -

Take a look at the Kahr barrel's innards. It looks like rounded off lands. Thats the hills and valleys. So lets suppose you get a traditionally rifled bore, and shoot the piss out of it. Lets say it wears out all those fine edges. What are you left with? Rounded off hills and valleys......

I think you'd be hard pressed to say that either would remain accurate longer than the other. You might SEE wear in the traditionally rifled barrel, but would it actually effect performance?

[Bawanna]

Golly Bawanna, you're quite cerebral this evening.

Why thank you Willie,



I think. Gotta look up cerebral, is that a good thing?

[CJB]

Its good as long as its not used along with words like hemorrhage, anomaly, contusion, atrophy, etc.

Cerebral is much better when used along with the word "bourbon".

[MikeyKahr]

Palsy, too.

[jocko]

I think I read where the bore diameter is smaller with polygonal rifled gun that standard rifled barrels, .. I think it was in that tutorial that bawanna posted about polygonal barrels..

[deadhead1971]

....nothing lasts forever...(well except jocko's PM9 maybe)...if it wears out, replace it.

I used to worry that my chrome-moly ar15 barrel would lose accuracy after 10,000 rds. But that will be 5-6 years from now, and new chrome-lined barrels are $200. So IF and when I wear it out, I'll just get a new one.

[Tilos]

The usual reason for ANY change is COST.

Engineers know Poly barrels are way CHEAPER to make...
And Marketing has convinced us Poly is BETTER.
YMMV
Tilos

[jocko]

....nothing lasts forever...(well except jocko's PM9 maybe)...if it wears out, replace it.

I used to worry that my chrome-moly ar15 barrel would lose accuracy after 10,000 rds. But that will be 5-6 years from now, and new chrome-lined barrels are $200. So IF and when I wear it out, I'll just get a new one.

dead right, we tend to worry alot about things that probably will not happen in our lifetime and at 10,000 rounds out of an ar15, accuracy would really have to go to hell before I would even worry about it. Not a target rifle anyway and 10K rounds is a hell of alot of shooting as u well know. When I got my PM9 I shot it like I stole it damn near every day. it accumulated alot f rounds. for me it is still excellent in all degrees. Is the barrel worn in 30K rounds, ???Hell I don't know.. I don't shoot it one bit better than when it had 500 rounds out of it. I know in 4 years I have worn some to. If one is worring about shooting out anything, just shoot less and enjoy it less and for what maybe saving a few hundred bucks at best. Naw, not for ol jocko, life is short the way it is and to save a few hundred bucks over the joy of shooting my PM9 is a no brainer for this ol timer. I shoot it like I stole it. If the fokker breaks tomorrow, I will fix it or go buy another one and not blink an eye over it. I have yet to read on any gun forum of any shooter SHOOTNG OUT A GUN AND DISCARDING IT. i HAVE A FRIEND IN iNDY WHO HAS A VOLVO WITH 960,000 MILES ON IT, now he has proabably put enough repairs and general maintenance in it to buy another volvo, but basically this car looks like the day he bought it. Guns to some extent are a maintenance product to, if u think not, then you probably should not own one.

He told me he has put over 25 sets of tires on this volvo and at today prices of around $400, that is 10K just in tires..

[RUT]

>>Forensically, it is apparently harder to get a match from a bullet that traveled through a polygonal bore<<

Aw man, I hope the LibTards don't get wind of this or that'll be the next thing to be banned! :(

[Bawanna]

Yup for sure. There was talk awhile back about required serial numbers on all bullets manufactured. Sounded like it was gonna put an end to reloading with no grandfather clause so people wouldn't stock pile millions of bullets. I guess the bullet manufacturers would be stuck with the unnumbered models.

Haven't heard anything about that now in months, maybe it was just a scare tactic.

[Willieboy]

Having serial numbered bullets would require a Bullet Czar in Washington. There goes the budget.

[aray]

As usual I think jocko nailed it.

But I'll add one more thing. I don't think polygonal bores vs. traditional ones make a whole lot of difference at self defense ranges. Over 7 to 30 feet, what are we talking about: one sixteenth to one eighth of an inch or something - max? The shooter's ability and technique are gonna account for way more of a difference.

Now if you want to talk about rifles when you're out scores or hundreds of feet then you're into the range where it might matter.

[jocko]

no rifling at 7 yards probably wouldn't matter alot either. I have no idea the price difference of kahrs premium lothar polygonal rifled barrels over Joe's blows barrel shop in timbucktoo, Iowa. I have no doubt kahrs polygonal barrle are as good as money can buy but at 10 yards and under, I serioulsly doubt if it was needed, But just maybe when kahr decided to make their first K9, they knew they had competition out there and they needed to be different in certain things that they could control at additional cost. If their goal was to make a super K9 (which they have certainly done), then someone in kahr said lets go with Lothar in Germany, their quality is not questioned by any gun maker etc.

[jocko]

well now we certainly do have choices in the PM and CM kahrs.

[WMD]

You can make the same argument regarding calibers.... which do you want to get killed with, a 38 spl or 44 mag? Both will do the same job at 7 yards.... most of the time. (might depend on what you are wearing)

The point of polyganol rifling is increased energy. The "Poly" rifling is a tighter seal causing higher pressures which equate to increased velocity which results in higher "knock down" energy. In a self defense handgun, this is a good thing. Especially if the calibers are smaller (e.g. 380).

We all use self defense ammo right? We do this to increase our advantage. The Poly rifling also increases our advantage with a bit more energy.

There are also a number of folks who believe that Poly rifling increases accuracy. There are two schools of thought on this one. Some say yes, some say no. I am not convinced that poly rifling produces better accuracy then standard land and groove rifling. (Sniper rifles are land and groove). By the same token, Poly rifling does not produce worse accuracy then land and groove either. Of course, this is only my opinion and we all know what they say about opinions... :D

There are a lot of factors that lead to accuracy in a handgun. Kahr has nailed it with their guns. Every one I have shot have been extremely accurate. That includes CW9's with land and groove barrels.