Barrel Fluting with regards to accuracy?

K

kiwi smith

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Hi Guys,

Can anyone please tell me how many of the top 20 (or 50) BR shooters at the super shoot or nationals shot with fluted barrels?

And if so, was it because they believe there is an accuracy advantage with fluting, or just a last ditch way of making weight limit without losing velocity due to a shorter barrel?



Thanks,

Dean.
 
Not sure what fluting could do to make a barrel more accurate. It is an attempt to maintain the stiffness of a large-diameter barrel and reduce its weight.
 
Would an unfluted barrel of smaller diameter, same length and same weight, be any less stiff? Would fluting increase the chances of inducing stress? If I remember correctly I don't think Hart Barrels believe in the fluting process.
 
martin zuck said:
Would an unfluted barrel of smaller diameter, same length and same weight, be any less stiff?
Click to expand...

Yes

Would fluting increase the chances of inducing stress?
Click to expand...
Maybe. I once asked Dan Lilja (he's an engineer) about this, and his reply was that fluting would redistribute any existing stress in the barrel more evenly. As to inducing new stress, he was silent -- I imagine because a significant factor might be the skill of the person doing the fluting?

The original poster asked about "top shooters" at "big matches." By in large, the average life of such a barrel is 250-400 rounds. Well. I'm not a top shooter, but I'd bet they don't think it would be worth the cost. Top shooters win a lot of barrels. At practice before a big match, they might have brought up to 10 barrels to try, & will pick the best based on how the barrel is performing then & there.

There are a number of things that top shooters do at big matches that aren't relevant for us middle-of-the pack guys, who expect 1,000 rounds out of a barrel, & at any one time, might have only two or three to pick from.

Having said that, I'd not spend money on fluting either. It is too easy to compute the weight of a barrel before fitting it.


FWIW
 
kiwi smith said:
Hi Guys,

Can anyone please tell me how many of the top 20 (or 50) BR shooters at the super shoot or nationals shot with fluted barrels?

And if so, was it because they believe there is an accuracy advantage with fluting, or just a last ditch way of making weight limit without losing velocity due to a shorter barrel?



Thanks,

Dean.
Click to expand...
Not to say there weren't any fluted barrels at the SS but I don't remember seeing any. SKipppy Otto could flute barrels that shot good. Billy Stevens has done some that still shot well but I wouldn't waste the effort. I remember pushing a patch down a fluted barrel that I was looking to buy and I could feel the irregularities. It was straight fluted though instead of spiral.
 
Spiral fluting will absolutely weaken a barrel (make it less stiff). Try supporting weight with a twisted I-beam.

A spiral fluted barrel will have very close to the stifness of a straight barrel of the minor diameter. I totally don't understand sriral flutting other than for appearance.

I have no proof, but I find it hard to get into my head that removing long strips of metal from a barrel would not in some small wat upset the internal dimentions of the bore. Unless the barrel was flutted and then reamed and rifled.
 
I was told by Frank at Bartlien Barrels that straight-fluting a cut-rifled barrel will stress relief it.
On a button-rifled barrel fluting should be done before the rifling, or it will induce stress.

I had SSG (StraightShot Gunsmithing) flute a 30" Bartlien #9 HV contour barrel for me with 6-flutes, 22" long, 0.090"-deep. I did it for two reasons: 1st- to reduce weight to be able to go to a longer/heavier barrel on my 1000-BR Lt-Gun; 2nd- to increase surface area for gains to barrel cooling.
Still in the early development stages of this barrel, so I can't speak to its full accuracy potential yet, but it has showed me great potential so far from its initial testings at 1000yds, and have shot a couple 5-shot groups in the 3's.

Happy Shooting
Donovan Moran
 
dmoran65 said:
On a button-rifled barrel fluting should be done before the rifling, or it will induce stress.
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Unless things have changed in the last 7-8 years -- and they may have -- you have to bore & rifle a button-rifled barrel before profiling. Don't know if anyone would want to profile an already fluted barrel...

Oddly enough, as I said earlier, Dan Lilja also said that fluting a barrel will relieve (evenly redistribute) existing stress. He was not against it, and Lilja barrels are button rifled.

Edit:

Well, I spoke to Dan about his willingness to have his barrels fluted over 10 yeas ago; he may have changed his mind. Certainly it was before Skip Otto passed. Don't want to mis-represent him. As I remember, he felt it was more effective to make weigh by calculating ahead of time...
 
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martin zuck said:
Would an unfluted barrel of smaller diameter, same length and same weight, be any less stiff? Would fluting increase the chances of inducing stress? If I remember correctly I don't think Hart Barrels believe in the fluting process.
Click to expand...

Hart flutes barrels with all kinds of flute patterns, straight, spiral, diamond, several patterns of interrupted flutes. It's Shilen that won't flute barrels. That being said, the late Skip Otto shot only fluted barrels that he had fluted himself and quite a few of them were Shilen barrels.
 
Thanks to all the guys who have taken the time to respond so far.

My concerns with regards to fluting are those of potentially weakening of the barrel, making it less rigid, on button-rifled barrels causing the bore to enlarge under the flutes if machining cuts are too deep, and of course the possible variation in fluting cut depth above the bore making the barrel pull to one side if the web-thicknesses (and hence the machining stresses) are not balanced. I have seen plenty of fluted barrels with bowed bores, and some from makers which i know normally produce fairly straight barrels (if un-fluted).

Personally i think the 'alleged' comment about fluting to create a stress-relieving effect on a barrel to be baloney.

I also think the alleged increased cooling effects to be only marginally better than an unfluted barrel. If any, in realistic terms.

My thoughts are that the act of fluting will do more to potentially ruin an otherwise good-shooting barrel, rather than enhancing it. Bottom line, if you can't prove a measurable increase in accuracy from fluting, then why do it?

Is it just because it is that some people will pay an extra couple hundred $$ for fluting, and if they want to to pay, then we'll do it???

Cheers,

D.
 
If you were to take a barrel, or any piece of material and flute/slot only one site, it will bend as that side has now been made weaker than the other, so the other side pulls and you get a banana. We just refer to have as stress in the material having been relieved, but barrel material usually has gone through a couple heat threat stress relief which at least reduces a lot of the induced stressed from when the material was made.
So does cutting flutes all around make it banana back into straightness, hopefully, but I sure don't see how it can improve accuracy, unless it wasn't straight at first and now it somehow is.
Has anyone taken a very close length measurement of a barrel before and are fluting, there might/should be a slight difference in length as indicator of stress changes.
Personally I don't like it from a plain pressure vessel design standpoint, where any surface irregularities create stress concentration. But it does look cooler.
 
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