Fluting a new Krieger Barrel

[mikeinlouisiana]

I am about to order a new Krieger RVC 7mm blank for a new build. yes this is my first build. I wanted to get fluted by Krieger folks.

I have a buddy that is telling me it is a terrrible idea? He said it puts much stress on barrel and will mess with accuracy. He has some fluted barrels and they don't shoot as good as the one that are not fluted. He also said Krieger will only air guage before fluting not after.

I thought fluting made the barrel stiffer and less harmonics which helps accuracy.

Any advice from the pros? To Flute or not to Flute?

Thanks

Mike

 

[Broz]

http://www.longrangehunting.com/forums/f19/flute-not-flute-78240/

http://www.longrangehunting.com/forums/f17/flutes-no-flutes-84196/

http://www.longrangehunting.com/forums/f26/looking-advice-fluted-non-fluted-59589/


That little search box at the top right of the page is a wonderful thing



Jeff

 

[Derek M.]

If your buddy is correct, tell him to call Krieger and tell them they are effin up their own bbls prior to selling them.

Krieger won't flute a bbl once it is off the lathe. If you want flutes, get them, and if the rifle simply won't shoot, let Krieger know.

I don't see how cutting steel off the outside of a bbl hurts it when cutting the inside of the bore does not. How would your friend reconcile that?

 

[Tikkamike]

Krieger stress relieves the barrels after fluting. if you want fluted I say do it.

 

[Edd]

I don't know what a 7mm RVC is but a fluted 7mm Krieger barrel will shoot fine. They won't flute a 7mm barrel smaller than a #6.

 

[calinb]

Krieger stress relieves the barrels after fluting. if you want fluted I say do it.

Yup! Probably even more significant to this issue is the Krieger single point cut rifling--at least according the the man himself, John Krieger (at 1:56):

 

[Bart B]

It's a popular shooting sports myth that fluting a barrel makes it stiffer. How could that possibly happen when you remove several strips of metal that made it as stiff as it was before fluting? What's stiffer, a floor with 2x6's stacked together side by side on edge or a floor with alternating 2x6's and 2x4's stacked the same way? Go figure that one out.

Fluting a finished button rifled barrel makes the bore and groove diameters a bit larger under the flutes. Hammer forged barrels get a bit smaller in the bore and groove dimensions. Cut rifled barrels change the least, but it's always best to flute the barrel before it's rifled and stress relieved. I know of folks getting their favorite button-rifled Hart match rifle barrel fluted and accuracy went south.......

Fluting does nothing for accuracy. It does help cooling a bit but any good barrel fit properly to a receiver won't change point of impact as it heats up firing 30 to 100 shots a minute apart. If barrels really did bend from heating up, then the precision test barrels used by arsenals testing mass produced 30 caliber match ammo shooting 200 to 300 shots into about 7 inches at 600 yards would never have happened.

Comparing a fluted barrel of the same length and weight of a solid one of equal length, the fluted one will be a little bit stiffer, maybe 10 to 15 percent. That's not enough to matter as far as accuracy's concerned.

Check out this site on barrel fluting: The Real Benefits of Barrel Fluting

Here's Kreiger Barrels' info on their fluted barrels: http://www.kriegerbarrels.com/Fluting-c1246-wp3392.htm

I'd rather put up with a few extra ounces of weight than take a chance on my barrel being ruined by fluting it.

 

[calinb]

<snip>... but it's always best to flute the barrel before it's rifled and stress relieved.

John Krieger didn't seem to have a problem with doing it afterwards with a cut-rifled barrel. He said there's really chance of getting into trouble with unrelieved stresess because there aren't any. The cut-rifling machinery Krieger uses permits fluting to be done before rifling the barrel, but the video gives me the impression that there's no risk in doing it later with John's barrels.

<snip>...I know of folks getting their favorite button-rifled Hart match rifle barrel fluted and accuracy went south.......

Well those were button-rifled barrels but it does bring up a potential problem, regardless. It seems to me that anytime you compare a fluted barrel with an otherwise identical but un-fluted barrel, you are comparing objects with different dynamic and harmonic characteristics. With any given load and rifle, the fluting might change the dynamics and end up making it shoot better or worse than an identical barrel without fluting. If you have a barrel that shoots great--even a cut-rifled barrel, it seems to me there is some risk in fluting for this reason alone.

 

[mikeinlouisiana]

I order the barrel with 10 each 3/6" flutes. I did it for weight, cooling and looks. I think its purdy!

Now comes the waiting.

Thanks for all the feedback

Mike

 

[Bart B]

It seems to me that anytime you compare a fluted barrel with an otherwise identical but un-fluted barrel, you are comparing objects with different dynamic and harmonic characteristics. With any given load and rifle, the fluting might change the dynamics and end up making it shoot better or worse than an identical barrel without fluting. If you have a barrel that shoots great--even a cut-rifled barrel, it seems to me there is some risk in fluting for this reason alone.

With two barrels of the same length and weight but one's fluted, the fluted one will be less rigid. It's resonant frequency with one end fixed in a receiver bolted in a stock will be lower that the solid barrel that's stiffer and has a higher resonant frequency. Most of the whipping at those frequencies is in the vertical axis, so the more rigid one will transit 2 MOA of bore axis angles at the muzzle in less time than the other. The fluted barrel will shoot bullets out over a greater elevation angle spread than the solid one.

Boy, I sure hope I got this right. All you mechanical enginners out there working with structural rigidity and the 4th order equasions used to calclate stiffness please check this out!!!!!!

 

[Edd]

With two barrels of the same length and weight but one's fluted, the fluted one will be less rigid. It's resonant frequency with one end fixed in a receiver bolted in a stock will be lower that the solid barrel that's stiffer and has a higher resonant frequency. Most of the whipping at those frequencies is in the vertical axis, so the more rigid one will transit 2 MOA of bore axis angles at the muzzle in less time than the other. The fluted barrel will shoot bullets out over a greater elevation angle spread than the solid one.

Boy, I sure hope I got this right. All you mechanical enginners out there working with structural rigidity and the 4th order equasions used to calclate stiffness please check this out!!!!!!

From Varmint Al's website.

CONCLUSION ON BARREL FLUTING....

When comparing two barrels of equal weight, length, and material but one is solid and other is fluted, the fluted barrel will have:

A larger diameter

Greater stiffness (depending on how the extra diameter/weight is distributed)

Vibrate at a higher frequency (depending on how the extra diameter/ weight is distributed)

Less muzzle sag (depending on how the extra diameter/ weight is distributed)

Fluting a solid barrel will:

Reduce its weight

Reduce its stiffness

Increase its natural frequency of vibration

Decrease its muzzle sag.

Reducing the weight of a barrel by fluting makes a stiffer barrel than reducing the weight by decreasing its diameter.

A shorter barrel of the same section, solid or fluted, will sag less and vibrate at a higher frequency.

 

[calinb]

<snip>Boy, I sure hope I got this right. All you mechanical enginners out there working with structural rigidity and the 4th order equasions used to calclate stiffness please check this out!!!!!!

Varmint Al provides an introduction:

Rifle Barrel Tuner Vibration Analysis

 

[Mikecr]

Comparing a fluted barrel of the same length and weight of a solid one of equal length, the fluted one will be a little bit stiffer

With two barrels of the same length and weight but one's fluted, the fluted one will be less rigid

Bart, you're contradicting yourself all over the place..

I say Krieger knows what they're doing.

 

[Bart B]

Bart, you're contradicting yourself all over the place..

I say Krieger knows what they're doing.

No, I'm only contradicting myself in one place. I just noticed that. Shame on me for doing that yesterday when I was tired and not thinking too well. Thanks for pointing that out.

'Course I'm the only one in these forums who's done that.