KAHR barrel difference regular vs polygonal rifling.

[medic579]

So the 4.0 barrel for the cw9 has the port, the added length and tge polygonal rifling. How much difference can the rifling make on a barrel this short?


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I am here: http://maps.google.com/maps?ll=30.447453,-84.262391

[Bawanna]

The CW has standard rifling. The average person or even above for that matter would never be able to tell the difference from shooting.

The plus to the standard rifling is you can shoot lead without worry. Not recommended with polygonal barrels.

[medic579]

Really, I didn't know that.


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I am here: http://maps.google.com/maps?ll=30.454035,-84.265181

[kahrlover123]

The CW has standard rifling. The average person or even above for that matter would never be able to tell the difference from shooting.

The plus to the standard rifling is you can shoot lead without worry. Not recommended with polygonal barrels.

Well, I'm not a pro shooter but I notice the difference in accuracy at 25 and 30 yards between the CM9 (standard) and PM9 (polygonal). I used +P ammo for this test.

[Thunder71]

Higher velocity is another benefit polygonal has over conventional.

[medic579]

Well who's shooting plain lead anyway. All I shoot is fmj and Speer gold dot + p

[medic579]

As long as it's jacketed right?

[OldLincoln]

Rifling comes up a lot here with Kahr having both styles. I found what I think is an excellent article to educate all of us on the matter.

Poly rifling:


Traditional Rifling: (75mm WWII)

[medic579]

I've read that several times. Sounds like the barrels are stronger. I don't see why it would be a problem. Do we know the twist rate of the polygonal vs standard on this barrel?

[CJB]

This much I know:

Its easier to hammer forge polygonal rifling in a barrel than the impression of cut rifling. Hammer forging the sharp edges is a chore. Its done, but its more work, harder to hold precise than polygons.

Remember hammer forging starts with a short fat barrel with a hole in it, thats HAMMERED into a long thin barrel which is formed around a mandrel with a positive image of the rifling on it. Because of that, polygons - with no sharp edges to hold sharp - are much easier to form.

Traditional land/groove rifling as we know it today is whats called "button rifled", whereby a positive shape "button" or plug, is pushed through the barrel blank under high pressure, effectively "ironing" the rifling image into the bore.

Cut rifling for lands and grooves is still done, but on a much smaller scale, mostly for custom barrels and small lot production. Thats because the gang-broach is much cheaper to produce than carbide plugs or mandrels. So for high production, you invest in the tooling for button rifling or hammer forging.

As to the difference between one and the other in a short barrel... personally I think you'd have to chrony a bunch of loads, thru a bunch of barrels before any conclusion could be drawn.