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barrel roughness near muzzle
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Ken Cline
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I was cleaning one of my rifles today, and noticed something strange upon close inspection of the bore. On the last 1/2" of the barrel at the muzzle, there appears to be some kind of machining marks on the lands of the barrel. The grooves in the barrel are not affected, they are smooth. I was wondering if this could have been from when they crowned the barrel. The crown and ends of the lands at the muzzle are very smooth and polished, but the lands 1/2" in from the muzzle are rough. It appears that this was made by something spun inside the barrel. I know it was not from anything I did in cleaning, etc. Will this have a major effect on accuracy? Is there a remedy?
 
Posts: 2852 | Location: Michigan | Registered: 02 September 2001Reply With Quote
tsturm
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quote:
Originally posted by Ken Cline:
I was cleaning one of my rifles today, and noticed something strange upon close inspection of the bore. On the last 1/2" of the barrel at the muzzle, there appears to be some kind of machining marks on the lands of the barrel. The grooves in the barrel are not affected, they are smooth. I was wondering if this could have been from when they crowned the barrel. The crown and ends of the lands at the muzzle are very smooth and polished, but the lands 1/2" in from the muzzle are rough. It appears that this was made by something spun inside the barrel. I know it was not from anything I did in cleaning, etc. Will this have a major effect on accuracy? Is there a remedy?

How does it shoot ?

 
Posts: 2361 | Location: KENAI, ALASKA | Registered: 10 November 2001Reply With Quote
Major Caliber
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The remedy is cut off the 1/2" that is rough.
 
Posts: 3097 | Location: Louisiana | Registered: 28 November 2001Reply With Quote
Robgunbuilder
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If your describing a factory barrel, then I've seen the same thing and they are caused by chattering of the rifling button. Sometimes it results in bad copper fouling and sometimes not. Interestingly, I've correlated my worst shooting gun with this problem, but have also seen it in others that shot fine. This is why many custom barrel makers insist you remove the last inch of barrel ( lilja cuts their barrels to force you to remove the last inch).If the gun shoots well, then don't sweat it. If not, Cut off an inch and recrown.
With all that said, if it's a custom barrel, lets hope it isn't the reminants of a lathe cut 60 degree center done by someone who didn't bother to remove the chips.-Rob
 
Posts: 6314 | Location: Las Vegas,NV | Registered: 10 January 2001Reply With Quote
Longbob
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This is an interesting thread to me. I have a Weatherby Ultralite in a 270 Winchester with the same problem. These are Kreiger barrels. They are supposed to be some of the better available. I have finally gotten it to shoot well with Hornady SST's and Nosler Partitions. You would think a Kreiger barrel wouldn't have these machining marks, but mine does.
 
Posts: 3512 | Location: Denton, TX | Registered: 01 June 2001Reply With Quote
Robgunbuilder
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The worst case of this I ever saw was on a Weatherby 30-378, from which you could mine copper. I have heard that these barrels come from Criterion which is related to Krieger. I used a bore scope on this thing and these marks were visable along the entire barrel and I have always assumed they were the result of the rifling process used. It sure wasn't lapped out and fouled unbelievably.-Rob
 
Posts: 6314 | Location: Las Vegas,NV | Registered: 10 January 2001Reply With Quote
scot
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In my younger more naive days I bought a brand new Remington m-700V in .223. I wanted an off the shelf rifle to shoot ground squirels, no muss not fuss. Well it wouldn't shoot for beans. I looked down the tube and notticed a ridge pattern in spiral fashon on both the lands and grooves for the full length of the barrel. I made a rubber casting of the bore using some foensic laboraatory casting material, "Microsil" it is called. This stuff reproduces every detail of a surface at the microscopic level. I examined the cast under microscope. The annular mark was infact a ridge on both the lands and grooves. It appears that a chip stuck on on the bore drill or the drill may have been chipped. DO they finish ream these things?? This barrel was a piece of junk and I had not even worn the blue off the inside. The bullet was traveling over profound hills and valleys. I don't know what they do for quality control but, it can't be much.

As an aside the stock looked like it was made by a trained beaver and finished in a bowling pin factory.

End of the story, I had a $700 action. I bought a Pac-Nor prefit tube and made a classic stock. Now it regurarly shoots under 1/2" and I have shot a few five shot groups in the teens. Looks good too.

[This message has been edited by scot (edited 03-28-2002).]

 
Posts: 813 | Location: Left Coast | Registered: 02 November 2000Reply With Quote
z1r
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Rob,

Regarding the lathe cut 60 degree center you spoke of, do you use a piloted center drill for this or just a plain old center drill?

Thanks,

Mike

 
Posts: 4868 | Location: Lakewood, CO | Registered: 07 February 2002Reply With Quote
CGB
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I have a couple of Winchester hammer forged bbls. that look like sewer pipe, and shoot about as well. I also have one in stainless that is very smooth and shoots well. Bad QC?
Do you know for sure if your barrel is forged, button rifled, or cut rifled?
C.G.B.
 
Posts: 238 | Location: Colorado | Registered: 05 June 2001Reply With Quote
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