2 stupid questions

[Flincher]

I've never owned a handgun with "polygonal" rifling until I recently purchased a P380. The rifling is barely visible in the barrel, and is not cut. So my 2 stupid questions are these.

1) how are these barrels made--is the rifling machined in

2) without "cut" lands and grooves, how the heck does the polygonal
rifling work ??:o:)

[MW surveyor]

1 - they can either be machined or forged around a mandrel.

2 - look down the barrel from the chamber end with it out of the gun. You'll see that it spirals.

[Flincher]

Thanks for the explanation MW surveyor !!

[MW surveyor]

You are very welcome. Sometimes I get things right.

[Geobob]

Hello, Flincher, and welcome from Missouri to a really great forum. Good people and info here!

And, best wishes for a safe, prosperous New Year to you and yours.

[ripley16]

Take a look down a CZ82 or 83 chambered in 9mm Mak. You'll swear it's a smoothbore. It isn't. It doesn't take much to get a bullet to spin.

My favorite polygonal barrel photo;
http://i72.photobucket.com/albums/i186/ripley16/Pistols/Heckler%20Koch/P7Chamberandbarrel.jpg
Love that chamber. :cool:

[Popeye]

Take a look down a CZ82 or 83 chambered in 9mm Mak. You'll swear it's a smoothbore. It isn't. It doesn't take much to get a bullet to spin.

My favorite polygonal barrel photo;
http://i72.photobucket.com/albums/i186/ripley16/Pistols/Heckler%20Koch/P7Chamberandbarrel.jpg
Love that chamber.

Your so right Ripley. Recently I managed to get my hands on a very nice unisssed CZ82. When I first looked down the barrel I thought how can a pistol with such little to no use have a barrel that looks like a smooth bore. The polygonal spiral is not as pronounced as it is on the PM9. It is a shooter though.
Welcome to the forum Flincher

[Flincher]

Thanks all for the informative responses and photo !!:)

[JFootin]

I'd like to see what Jocko's PM9 barrel looks like after 32,000 rounds! I wonder if the bullets tumble and keyhole? Wonder if that is why he shoots it with the accuracy of a blunderbuss? LOL! I'm just ribbing you, Jocko! :boink:

[Flincher]

I'd like to see what Jocko's PM9 barrel looks like after 32,000 rounds! I wonder if the bullets tumble and keyhole? Wonder if that is why he shoots it with the accuracy of a blunderbuss? LOL! I'm just ribbing you, Jocko! :boink:

I'm really going to enjoy this forum. Seems like you people have more fun than the other thread I spend time on. I can stand a little good ribbin' my ownself once in a while.:D:D

[Bawanna]

Well far be it from me to point out small details and all but you installed the handle on your revolver there bass ackwards or maybe not I guess depending on our mood and disposition at the time.

Something to take into consideration none the less.

[Flincher]

Well far be it from me to point out small details and all but you installed the handle on your revolver there bass ackwards or maybe not I guess depending on our mood and disposition at the time.

Something to take into consideration none the less.


Well Bawanna, I'm here to inform you that is a photo of the official sidearm of the NDNTDL. The NORTH DAKOTA NORWEGIAN TERRITORIAL DEFENSE LEAGUE.:D:D

[Bawanna]

Well Bawanna, I'm here to inform you that is a photo of the official sidearm of the NDNTDL. The NORTH DAKOTA NORWEGIAN TERRITORIAL DEFENSE LEAGUE.:D:D

Well slap me and call me daddy I didn't know North Dakota had a Norwegian Territorial Defense League.

Learn something every day. I was ready for something Kervorkian.

[getsome]

Hello Flincher and welcome to Kahrtalk...This is by far the best gun related forum on the web, lots of good fun along with some serious question/answer discussion about all things Kahr or any other firearm for that matter....

Colonel Bawanna and Greg are great mods and let us have fun and pretty much anything goes to a point and then it will be corrected but all in all life here is lots of fun and a great place for meeting new friends and learning about Kahrs and the shooting sports in general....WARNING: Kahrtalk can become addictive...

Again, Welcome aboard and if you got a spare one of those backwards revolvers please ship it to: Senator Dianne Feinstein c/o Commiefornia State Capital/ US Senator offices with a note that this is the newest assault weapon and she should try it out immediately if not sooner for the protection of us all!!!!....:yo:

[Bawanna]

You know thats a fine idea. They gave Reagan and both Bush's fine firearms during their presidencies. I'd send one to the current resident of the WHITE house. Seems only fitting.

[Flincher]

Hello Flincher and welcome to Kahrtalk...This is by far the best gun related forum on the web, lots of good fun along with some serious question/answer discussion about all things Kahr or any other firearm for that matter....

Colonel Bawanna and Greg are great mods and let us have fun and pretty much anything goes to a point and then it will be corrected but all in all life here is lots of fun and a great place for meeting new friends and learning about Kahrs and the shooting sports in general....WARNING: Kahrtalk can become addictive...

Again, Welcome aboard and if you got a spare one of those backwards revolvers please ship it to: Senator Dianne Feinstein c/o Commiefornia State Capital/ US Senator offices with a note that this is the newest assault weapon and she should try it out immediately if not sooner for the protection of us all!!!!....:yo:

I should have at least one spare after next months new recruit shooting qualification tryouts:D:D

[muggsy]

I'm really going to enjoy this forum. Seems like you people have more fun than the other thread I spend time on. I can stand a little good ribbin' my ownself once in a while.:D:D

I could tell by your avatar and handle that you're our kind of guy. The only one on this forum who takes himself seriously is old Jocko. Don't mess with him. He'll pee on your Fruit Loops. BTW, there are no stupid questions for which we have no stupid answers. We're all professionals here. Welcome aboard.

[CJB]

1) how are these barrels made--is the rifling machined in

2) without "cut" lands and grooves, how the heck does the polygonal
rifling work ??:o:)

Polygonal rifling is all made by hammer forging. Due to its very nature, it cannot be cut, due to lack of space for chip removal, or button formed, because of the pressures and deformation that would be caused.

Hammer forging is a process whereby a blank that is short and fat and smooth on the inside, is "hammered" on the outside, to make it long and skinny. While they do this, a mandrel, with the positive image of the rifling - either traditional or poly - is inside the barrel blank. When done, the mandrel is withdrawn, leaving a (hopefully perfect) image of the mandrel on the inside of the barrel.

Poly rifling works fairly well. Kahr touts it as "match grade" but in truth, its no better than any other hammer forged rifling, about the same as button rifling, and not as nice (for accuracy) as cut rifling. No major target barrels are made from hammer forged process, that I know of at least.

They're not bad, in poly or traditional... just that variations exist within the process... along the length of the bore. With cut rifling you can do gain twist, taper, both... etc... not possible with button or hammer forging.

Once set up to do, hammer forging is incredibly inexpensive, slightly less expensive than button rifling, and far far less expensive than cut rifling.

Almost all commercial barrels - Remington, Winchester, Ruger, Sako, Savage, Browning, you name it... use hammer forged barrels. You get good results, but... real accuracy still comes from cut rifling.

Hope that helps!

[AIRret]

Very interesting, I'm always learning from you folks.
Out of curiosity, what would a cut barrel cost vs. a hammer forged barrel?
I'm not in the market, I'm just interested.

[CJB]

Actual cost, or even percentage... hard to say.

Here's what's involved for hammer forging.

A worker sets a short skinny blank on the machine, the machine does the work. Blanks are then cut up for pistol lengths, or used more or less full length for rifles. Most hammer forged rifle barrels have the chamber forged right into the barrel. Pistol barrels, because they're cut from a long blank, are individually chambered later.
Rifle barrels are then turned to the proper outer taper on a lathe that centers the bore concentrically within about .001-.002 or so. Not super high precision, but tighter than turning from the outside centering would do. The barrel will then be air gauged, and straightened. Based on the chamber depth, the shoulder is cut, and the end is threaded. The other end is cut to length and crowned. Those are all machine processes. When the barrel is fit to the action, final trimming is done, if needed. In production, they can leave the end of the barrel maybe .005 to .015 short, and it doesn't hurt much (although Mauser and Hatcher say its not great for accuracy). A worker polishes the action and barrel, and it gets drilled and tapped for sights then blued. Done.

Sounds like a lot, but... its all machine work. Very high grade, very precise, special purposed machine work.

For cut rifling... you start with a blank. The blank, instead of being short, is full length. It has to then be deep drilled very precisely. Usually they're deep drilled a few .001's undersize then deep reamed to final bore size. The reaming process is done by hand, by a worker. A very skilled worker, who must feel for chips and constantly flush and clean the cutter and barrel during the reaming. Then, the blank is put on a rifling machine (sort of like a lathe, but different) and the gang broach is pulled through the barrel - again by feel. Gang broaches are progressively enlarged until final groove depth is achieved. This results in a barrel blank with no chamber, and whose rifling doesn't quite line up at one end. It will have miniature steps in the grooves/lands as the progressive broach cutters find their way and finally align with whats already cut. That end of the barrel is cut off by an amount that will let the chamber use any remaining uneveness. The barrel is chambered with three chambering reamers first, second and finish. Only first and second are used now. This is done for speed, semi by hand. The rest of us would use two reamers very slowly second and finish, only second now. After that, the bore is lapped with a lead slug that has been impregnated with lapping compound. This is done by hand, progressively, and by feel and by eye... to achieve the correct bore finish and not disrupt the fine edge of the cut rifling. Then the barrel is tapered, shouldered and cut with enough room that the chamber may be finish reamed, in the action, and the chamber is polished. The rest after that is the same.

As you can see - the hand work, by skilled workers, is huge when you make a precise
cut rifled barrel. Harry Pope, who made his own barrels from solid, used to take a day to drill and ream, and a day to cut the rifling, and a day to fit the barrel to the action. He himself stated that even with the long list of barrels to make, with a two year or more wait... he never even broke even, and didn't do well financially at all. It was passion for him. The less passionate can no doubt work with more speed, and less sweat and precision.

[Gangplank]

wiki is your friend:
http://en.wikipedia.org/wiki/Polygonal_rifling

http://upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Hammer_forged_6-right_polygonal_rifling_pattern.png/220px-Hammer_forged_6-right_polygonal_rifling_pattern.png

[CJB]

someplace I have a picture of a raw hammer forged Ruger barrel... it basically has the same twist on the outside as the rifling has on the inside.

Found one of 'em... not great.
http://img.photobucket.com/albums/v214/bandersnatchreverb/Firearms/P1220141.jpg

Thats what a hammer forged barrel looks like "raw". That one was made as a blank by Ruger for Clark Custom Guns, who did the chamber, crown and shoulder (and extractor cut).

[JFootin]

CJB, how does the conventional rifling in the C series Kahrs differ from the cut rifling?

[CJB]

In a barrel that short.....zero discernable difference.

[CJB]

Let me elaborate a little more....

We don't know what sort of rifling is used in the C series barrel. Could be button rifled, or hammer forged. I don't think Kahr has stated... but I'm open to correction.

Cut rifling proponents like to talk about no stresses put on the barrel, the sharpness of the rifling, the way they can be hand lapped and sized for a tapered bore (smaller at the muzzle by 1/2 a .001 or so), and gain twist - starting slow and getting faster down the tube. This is all good for VERY accurate bolt rifles.

In a pistol... there is so much slop in the rest of the mechanism, and the barrel is so short, and ammo so inconsistent in the short barrels, it just doesn't matter.

Put another way, if you had two barrels that are 3 inches long, and somehow benched them out of the pistols, and fired them, the difference in rifling would amount to very close to nil, because of ammo inconsistency in such a short tube. I have no guess as to actual results on paper... at 25 yards... almost nothing. Now add the slop of barrel to slide fit, barrel/slide to frame fit... and you'll see that that matters so much more. Then add in the factor of the human hand and eye... and we're worried about rifling? I seriously think not!

You realize that soft little clover leaf patterns have been shot with stock Colt 1911 barrels made during wartime production, from "accurized" 45's. In the day, the gunsmith would fit the slide tight by squeezing it, then hand lapping it. Then he'd fit the barrel by welding metal onto the hood and bottom. Sure, chambers would be .010 long... oh well. Then tight bushings would be fitted, and triggers tweaked. And those guns, from sandbags with a good shooter and good ammo would group at 1/3 to 1/2 of the X ring which is 1-5/8 inches. That pretty much would have all shots touching. Cut rifling would do nothing extra, as that is the limit of what the pistols could mechanically do and still function as a pistol.

[Flincher]

Great forum, and a very interesting, informative, and educational thread ( with a little humor thrown in).:):)