Desert Fox

PacNor Polygonal Barrel What a Disappointment

13 posts in this topic

The factory barrel on my 300 Win Mag Model 70 Laredo finally gave up it's ghost so I sent it to Jim Gruning shop to have it re-barreled. I ordered one of PacNor Polygonal barrel and have Jim profiled it to match the factory contour. During barrel break in, I noticed severe copper fouling after every shot. The rifle shoots tight but it takes a lot of scrubbing to get the copper out. Talked to Jim and he told me to bring the rifle back and he'll lap it. If the fouling does not improve, I'll send the barrel back to PacNor accompanied with a nice love letter.Here's the 2 - 3 shot group. 165 grain Nosler Accubond on the upper right and 168 grain Nosler Comp on the lower left.IMG_0073.jpgIMG_0072.jpg

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5R is different type of rifling than a Polygon. David Tubbs use Schnider's polygon in his competition rifle and swears by it. Glock and Desert Eagle pistol barrel is a good example of a polygonal barrel. PacNor design however differ slightly than those two examples.

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Hey Rommel, is that the match or super match barrel? I have a 3 groove, PacNor SM on a 22.250 and it shoots good, not as good as my Kriegers or Bartlein but consistent.

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Hey Rommel, is that the match or super match barrel? I have a 3 groove, PacNor SM on a 22.250 and it shoots good, not as good as my Kriegers or Bartlein but consistent.
Frank, I'm not sure if the polygon is a super match but the price sure reflect that of a super match. I have a 3 grove 12 twist Supermatch on my 308 and it's a shooter also, just as good as my Broughton and KP. This is my second PacNor and I'm still waiting for a response from my inquiry. I'll have it lap first and see what happens.

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Isnt the TC Venture poygonal? Im not doubting your knowledge, its just something that I thought I read somewhere.
Grant, i'm just not familiar with the TC Venture. But if TC claimed that their rifling is 5R then it's a different type of rifling than a Polygon. 5R was popularized by Obermeyer although was not the originator of the design. Actually it's was the Russian who came up with it. It's now copied by every barrel manufacturer in the US. 5R barrels has canted land whereas the Polygonal has no defined land and groves. Instead it has rifling that shapes like a rounded polygonal pattern that resembles an octagon or a hexagon. The design is supposed to have a good gas sealing characteristics hence increase in velocity and reduce bullet deformation.

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Even though it used a hex shape I always thought that the Whitworth rifle was the grandady of the various round cornered bore rifling styles. :)

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If you end up ordering another barrel, Id recommend Benchmark up out of WA... great guys and make a nice stick...

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Thanks Novaman. I heard nothing but good things about Benchmark also. You can't go wrong with any of the premium barrel in the market these days... they're all good. I have my faith with PacNor. They make accurate barrel, and I know they'll take care of their customer.

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I ordered a PacNor for my 300, three groove, 26 in. #5 fluted. They gave me a 13 week delivery date,so the barrel business must doing be good. I hope it's a shooter. I should see it some time in Feb. I'll give full report when I get it finished.,,300wsm

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You can't go wrong with 3 grove. LiLja start making them also. I have one of his 6.5-8 twist no-3 that I'm saving for my 6.5-284.Going back to the PacNor on my 308. I once developed load to match the factory 168 grain Federal Gold Medal Match using Nosler Competition bullet and BLC-2 powder. I had two sets of loads with half a grain difference in powder weight. I fired 2-5 shot groups @ 110 yards using both loads and as you can see from the target below, all nine clustered together with only one bullet missing the group, obviously from operator error. This is the kind of accuracy PacNor are capable of delivering. IMGP1990.jpg Here's with 155 grain Lapua Scenar IMGP1895.jpgHere's a 3 shot group at 510 yards with 155 grain Lapua Scenar that measured 1.048"Target016.jpg

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