Gunsmithing Flute my new Bartlein or not?

JGorski

JGorski

Gunny Sergeant
Full Member
Minuteman
Oct 25, 2011
2,991
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Central Wis.
#1
Im wondering if there's a real benefit to fluting a HV barrel, or is it more of a balance thing, more stiffness, can it all come together and make the rifle more accurate?? Thoughts?
Chad, How much do you charge for that service?
 
#2
Re: Flute my new Bartlein or not?

Fluting reduces weigh, most ive seen was just over one pound. Just depends on barrel contour and caliber. Fluting increases surface area, increasing cooling. By how much? I have not tested it yet. A fluted barrel will be stiffer than a non fluted barrel of the same weight. I dont know that fluting will increase the stiffness of a barrel, i cant see fluting increasing accuracy, but it can decrease accuracy say in a button rifled barrel that has not been properly stress relieved
 
#4
Re: Flute my new Bartlein or not?

Fluting just looks cool. Cool looks gets you chicks.

Treat it as such.
smile.gif


$175.00 buys you six flutes. Each additional is $25.00


It should help with a barrel cooling off a bit sooner. You are adding surface area which should aid in convection.

Your also taking away mass which means the barrel is likely to heat soak that much sooner.

I don't profess to have any formal understanding of thermal dynamics so treat my response for what it is; a total guess.
smile.gif


It does remove weight. How much? One could sit and figure it out I guess, but if your really looking for a barrel on a diet you get two primary choices; shorten it and/or make it smaller.

Stiffness, inducing stress, relief of stress, and button vs. cut are subjects I'm not touching because they seem to bring the "night crawlers" out in droves and that's when threads erode into a cruel internet joke.

C.

 
#5
Re: Flute my new Bartlein or not?

Karl Kampfield is the guy to talk to for helical fluting. I've not yet taken the time to build the fixturing to do this. I've had several examples of Karl's work here in the shop and they are immaculate. He does a killer job.

C.
 
#6
Re: Flute my new Bartlein or not?

I'm not sure what to think about a fluted barrel. I have been shooting a Rock Creek 5R Rem varmint contour barrel and it shoots great. After 1,500 rounds I set it back 0.05" and it continues to shoot great.

For my next barrel I picked up the same make and contour but fluted. With one of each type, in each hand I can hardly tell the difference. We slapped one on my team mates rifle which is a sister to mine and cant tell a lick of difference.

I think C Dixon is right, it just looks cool.
 
#7
Re: Flute my new Bartlein or not?

There are two honest reasons for fluting:

1) oops, I didn't quite make it under max weight for a restricted class.
2) chicks did it.

If you want it because you like the looks, it's your rifle and your money to spend as you wish, go for it. If you want a lighter rifle, start with a slightly different contour and save the money. If you want to use cooling as a reason, first you must convince yourself that heat is a problem in bolt rifle conditions.

Sure I have fluted barreled rifles in my safe. Some I did simply because I could. Others came that way. The way I see it, it's an unnesssary expense added on top of a consumable item.
 
#8
Re: Flute my new Bartlein or not?

Like 300sniper says and I tell guys the same thing.

It will reduce weight because your taking metal off of the barrel.

Does nothing for accuracy. The way some barrels are made it can hurt accuracy as well as if the fluting is to deep it can have an impact on accuracy as well.

I will say for the most part it does not make the barrel more stiffer. If you say it does then I want to ask how are you measuring it?

For some people they just like the way it looks.

I would never flute a button rifled barrel.

Later, Frank
Bartlein Barrels
 
#10
Re: Flute my new Bartlein or not?

I've always assumed that fluting would make a barrel stiffer for a given weight, but just for kicks I ran a FEA simulation. I was suprised by the results. Both barrels use the same base model. I added 6 x 1/4" round flutes and ran the test again. The blank has a 1.25" diameter at the base and a straight taper to 1" at the crown. 28" OAL. I fixed the tennon and applied 5lbs of force to the muzzle perpendicular to the axis of the bore.

The unfluted has .28mm displacement. The fluted has .014mm displacement. I'm not sure I trust these results because of the extreme difference, but I thought it was interesting enough to share. (The displacement is shown 491x normal)

If I had two physical models I would set up an indicator and hang a known weight from the muzzle to verify the results, but unfortunately I don't.



Unfluted:
Unfluteddisplacement_zpse5d779c3.jpg


Fluted:
Fluteddisplacement_zpsb9e22fbf.jpg
 
#13
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dave Tooley</div><div class="ubbcode-body">So much for modeling. I've found common sense and the target tells me most of what I need to know. </div></div>

BINGO!!
 
#14
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: C. Dixon</div><div class="ubbcode-body">Karl Kampfield is the guy to talk to for helical fluting. I've not yet taken the time to build the fixturing to do this. I've had several examples of Karl's work here in the shop and they are immaculate. He does a killer job.

C. </div></div>

It's actually Karl Feldkamp, and his outfit is called Kampfeld Customs.
 
#15
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dave Tooley</div><div class="ubbcode-body">So much for modeling. I've found common sense and the target tells me most of what I need to know.

I'll be fluting barrels in the next few weeks. I'll do a simple static test using the same barrel blank. </div></div>

Yeah, I've been using the virtual modeling to test injection molded parts for almost a decade now and I'm still not comfortable enough to bank a design on the simulations without some empirical support.

I'll be very interested to see your results.
 
#16
Re: Flute my new Bartlein or not?

Not trying to step on Chad's or Mr. Tooley's business, but here is a site from a guy that does neat work.

http://twistedbarrel.com/

He's not associated with the Hide, but is a nice young guy trying to get a start. Resonable prices, quick turn around, just good to deal with from what I hear. He's located in Douglas, WY, home of the SH cup.
 
#17
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrm850</div><div class="ubbcode-body">I've always assumed that fluting would make a barrel stiffer for a given weight, but just for kicks I ran a FEA simulation. I was suprised by the results. Both barrels use the same base model. I added 6 x 1/4" round flutes and ran the test again. The blank has a 1.25" diameter at the base and a straight taper to 1" at the crown. 28" OAL. I fixed the tennon and applied 5lbs of force to the muzzle perpendicular to the axis of the bore.

The unfluted has .28mm displacement. The fluted has .014mm displacement. I'm not sure I trust these results because of the extreme difference, but I thought it was interesting enough to share. (The displacement is shown 491x normal)

If I had two physical models I would set up an indicator and hang a known weight from the muzzle to verify the results, but unfortunately I don't.



Unfluted:
Unfluteddisplacement_zpse5d779c3.jpg


Fluted:
Fluteddisplacement_zpsb9e22fbf.jpg
</div></div>

That FEA is wrong, somehow. It doesn't pass the sanity test.

The .28mm (.011") deflection of the unfluted barrel is reasonable, but the .014mm (.00055") deflection of the fluted barrel is not reasonable.

No way can you hang 5lb off a 28" long, 1.5" diameter cantilevered beam (barrel) and deflect 1/2 a thousandth of an inch. No way. Something is messed up.

Not that it makes much difference, but is there a bore in your model? Diameter? How about rifling??? :)
 
#18
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrm850</div><div class="ubbcode-body">I've always assumed that fluting would make a barrel stiffer for a given weight, but just for kicks I ran a FEA simulation. I was suprised by the results. Both barrels use the same base model. I added 6 x 1/4" round flutes and ran the test again. The blank has a 1.25" diameter at the base and a straight taper to 1" at the crown. 28" OAL. I fixed the tennon and applied 5lbs of force to the muzzle perpendicular to the axis of the bore.

The unfluted has .28mm displacement. The fluted has .014mm displacement. I'm not sure I trust these results because of the extreme difference, but I thought it was interesting enough to share. (The displacement is shown 491x normal)

If I had two physical models I would set up an indicator and hang a known weight from the muzzle to verify the results, but unfortunately I don't.



Unfluted:
Unfluteddisplacement_zpse5d779c3.jpg


Fluted:
Fluteddisplacement_zpsb9e22fbf.jpg
</div></div>

The last test I did several years ago the fluted barrel flexed more. Here is what I did.

I took two barrels the same contour. I believe they were heavy Palma contours 30" finish length/31" blanks.

I put the barrel blanks into a bench center. I then put a dial indicator in the middle of the barrel on the o.d. I then took like a 20# or 30# weight or something in that range. I set the weight right on the middle of the barrel. The fluted barrel flexed like .020" -.030" more then the non fluted barrel. The fluted barrel had like 8 flutes around .187" wide.

but.....

How the barrel when installed on the action and you chamber and fire rounds how it behaves under recoil etc...can be totally different then putting the barrel in a bench center and setting a weight on it.

Like Dave Tooley also mentioned. What the gun does during physical testing on paper out in the real world will tell you more than some of the modeling or calculations that you can do on a computer.

I'll see if we got a couple of identical contour/caliber barrels with again one being fluted and one not and do the test again. Will let you know.

later, Frank
Bartlein Barrels
 
#19
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">
That FEA is wrong, somehow. It doesn't pass the sanity test.

The .28mm (.011") deflection of the unfluted barrel is reasonable, but the .014mm (.00055") deflection of the fluted barrel is not reasonable.

No way can you hang 5lb off a 28" long, 1.5" diameter cantilevered beam (barrel) and deflect 1/2 a thousandth of an inch. No way. Something is messed up.

Not that it makes much difference, but is there a bore in your model? Diameter? How about rifling??? :) </div></div>

Whoops- You are all right. I'm not sure what parameter I had wrong but I re-ran the simulation and it came out much more like I thought it would.

The model was for comparative purposes so I just plugged 4340 in as a material because it was already entered into the database and I omitted the rifling. There is a .308" Bore however.

The unfluted barrel results were identical to the first test.
The Fluted barrel however was dramatically different. .32mm displacement.
Fluteddisplacement2_zpsb21f150d.jpg
 
#20
Re: Flute my new Bartlein or not?

Frank,

Using the cylinder section I was going to clamp an unfluted barrel in milling machine vice. Set up an indicator and put a load on the muzzle and measure the deflection. Then take that same blank, flute it and hang the same weight in the same setup. While I was at it orient the flutes in different positions to check out an old wives tail. 1. Flute at 12:00 then 2. a solid section at 12:00
 
#21
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Frank Green</div><div class="ubbcode-body">
...

How the barrel when installed on the action and you chamber and fire rounds how it behaves under recoil etc...can be totally different then putting the barrel in a bench center and setting a weight on it.

Like Dave Tooley also mentioned. What the gun does during physical testing on paper out in the real world will tell you more than some of the modeling or calculations that you can do on a computer.

...

later, Frank
Bartlein Barrels </div></div>I'm not sure in which direction, but I could definitely imagine that fluting would affect the barrel frequency. Would it be higher freq because of the reduced mass, or maybe slower due the increased displacement? Maybe it's a wash and the end result is the same.
smile.gif


I posted the tests because I thought it might lead to interesting conversation. In the end I will still trust the experienced opinions.
 
#22
Re: Flute my new Bartlein or not?

One of the keys to remember here in this discussion is that it is usually stated that a fluted barrel <span style="text-decoration: underline">of the same weight</span> as an unfluted barrel will exhibit less deflection. That is different than comparing a fluted to non-fluted barrel that started life as the same contour.

Assuming lengths are equal, a <span style="text-decoration: underline">same weight</span> barrel comparison now means you are now comparing a smaller contour unfluted barrel to a larger original diameter fluted barrel. Stiffness is directly proportional to the Moment of Inertia (Generally depicted as I) property of the section. I not only takes into account the mass, but is a function of how far that mass is from the neutral axis (in this case, the center of the bore). Depending on the shape, I is usually a function of this distance to the fourth (^4) power multiplied by the mass. In layman's terms the distance the metal is from the center of the bore has a dramatic effect on stiffness. While mass also has a role in I, your biggest gains in I are most easily achievable by increasing distance. It is the idea behind why the flanges in an I or W beam are separated by a web. The longer the web (Deeper the section), the more resistance to deflection those same weight flanges can provide. All subject to lots more rules and phenomena (like lateral torsional buckling, etc.)

Now, if we consider two blanks of the same contour (Franks example above), the distances are the same, but the unfluted barrel has more mass. Thus it will always have more stiffness.

These are all pretty gross simplifications, but are hopefully illustrative of the concepts being discussed.

ETA - jrm's simulations (revised ones anyhow) show the same results - fluted barrel of same original contour as unfluted barrel will always have more deflection. Material science 101.
 
#23
Re: Flute my new Bartlein or not?

So we have some very aggresive flutes at .250"W X.250" deep. We lost approxamately %14 in stiffness for a sizeable weight reduction. I know from experience you reach a point of diminishing returns rather quickly when comparing barrel weight VS accuracy with all but the larger more violent calibers. So the question is why don't we go with larger diameter barrels and flute more? My guess is we have long since reached a point of diminishing returns and we can't see it on the target.

One more thing fluting does besides add sex appeal and just remove weight. It also changes the balance of the rifle. Take a 12 lb. rifle and reduce the load 12 ozs. in your off hand. Over time it will make a considerable difference.
 
#24
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dave Tooley</div><div class="ubbcode-body">So we have some very aggresive flutes at .250"W X.250" deep. We lost approxamately %14 in stiffness for a sizeable weight reduction. I know from experience you reach a point of diminishing returns rather quickly when comparing barrel weight VS accuracy with all but the larger more violent calibers. So the question is why don't we go with larger diameter barrels and flute more? My guess is we have long since reached a point of diminishing returns and we can't see it on the target.

One more thing fluting does besides add sex appeal and just remove weight. It also changes the balance of the rifle. Take a 12 lb. rifle and reduce the load 12 ozs. in your off hand. Over time it will make a considerable difference. </div></div>


Starting with a slightly different profile barrel will give a similar balance as a fluted barrel and cost less. If we're talking about rifles that will be shot offhand, I doubt the lighter profile would be any less accurate than a fluted barrel.
 
#26
Re: Flute my new Bartlein or not?

I don't know about doing it now... I know when Satern makes barrels he flutes them before either boring or rifling them. Something to do with stresses and then relieving the stresses, I think? Anyway, I consider this guy the master when it comes to super accurate, cut rifle barrels.

I don't know if you can do this afterwards, but KAC "flutes" their barrels on the SR25ECC model by boring hemispherical dimples all over the barrel. It is ingenious when you consider it, it greatly increases surface area because the dimples are all over and not restricted to a furrow, and it shouldn't decrease barrel strength, or stress it nearly as much, because there are no continuous grooves or faults. I'm definitely keeping this in mind when I have another barrel made if I want it lightened.
 
#27
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrm850</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">
That FEA is wrong, somehow. It doesn't pass the sanity test.

The .28mm (.011") deflection of the unfluted barrel is reasonable, but the .014mm (.00055") deflection of the fluted barrel is not reasonable.

No way can you hang 5lb off a 28" long, 1.5" diameter cantilevered beam (barrel) and deflect 1/2 a thousandth of an inch. No way. Something is messed up.

Not that it makes much difference, but is there a bore in your model? Diameter? How about rifling??? :) </div></div>

Whoops- You are all right. I'm not sure what parameter I had wrong but I re-ran the simulation and it came out much more like I thought it would.

The model was for comparative purposes so I just plugged 4340 in as a material because it was already entered into the database and I omitted the rifling. There is a .308" Bore however.

The unfluted barrel results were identical to the first test.
The Fluted barrel however was dramatically different. .32mm displacement.
Fluteddisplacement2_zpsb21f150d.jpg
</div></div>

Its pretty simple if you think about the fundamentals. A fluted barrel cannot have the same stiffness as an unfluted barrel of the same physical properties as there is more material at the O.D in the unfluted profile. Simply removing material will always reduce stiffness to some degree. A geometric adjustment is required to compensate for the removal of material.

So the comparison should be between fluted and unfluted barrels of the same weight. The unfluted barrel must have a smaller outer diameter while the fluted barrel will have a larger O.D. but a smaller core diameter to keep weight constant. For materials of constant properties stiffness is a function of geometric shape and in this case the profile with material furthest from the centre will be stiffer i.e fluted. This is the point of fluting, for the same weight you can get more stiffness but the OD has to be larger.

I am not sure this is what was modelled as the core diameter needs to be reduced to get a true weight for weight comparison?
 
#28
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dave Tooley</div><div class="ubbcode-body">Frank,

Using the cylinder section I was going to clamp an unfluted barrel in milling machine vice. Set up an indicator and put a load on the muzzle and measure the deflection. Then take that same blank, flute it and hang the same weight in the same setup. While I was at it orient the flutes in different positions to check out an old wives tail. 1. Flute at 12:00 then 2. a solid section at 12:00 </div></div>

I'm kinda ahead of you but I didn't think about where the flutes where orientated when I did the test late yesterday.

Both barrels are c.m. steel.

I took two barrels. Same contour (for reference pretty close to our #14 contour) but one barrel was a .300 win. mag and the other .338 Lapua. Yes I know got a variable going already but read on.

Both barrels, same contour and finish length one is fluted (.338cal.) the flutes are .100 deep x approx. .25" wide and the other is not fluted (.300win.).

I put both barrels in the bench center and put a dial indicator on them in the center of the barrel blank. I then set a 24.8# weight in the center area of barrel.

The fluted barrel flexed .007".
The unfluted barrel flexed .005".

The next thing I did was I thru the barrels in the lathe (3 jaw chuck and I had one of the jaws located at the 6 o'clock position) and clamped on the straight section on the breech end in basically the same spot (both barrels are threaded on the breech ends and I did not chuck on this area).

I put my dial indicator on the muzzle end and set the same 24.8# weight right in front of it at the muzzle end.

The fluted barrel flexed like .090".
The unfluted barrel flexed like .060".

What I didn't like about this test was I only had about 2" of straight section on the breech end to clamp on. Now throw in the factor of wear on the jaws etc...I didn't feel this test was the best so......

I took both barrels and using a 5C collet I clamped on the threads. The thread length is approx. 1" maybe a tad longer. I pushed both barrels up to the shoulder and clamped them as tight as I could.

With the dial indicator on the muzzle end the readings I got where:

Fluted barrel flexed approx. .055"
Unfluted barrel flexed approx. .055" as well.

Both barrels on the last test I repeated it a few times each and I would give it a +/- .005" on the readings.

It was just a quick test. I'll work on it some more to make sure I'm clamping on the as tight/solid as I can. Ideally a collet type clamp that can go big enough to clamp on the straight o.d on the breech end would be better I don't have a 5C collet big enough to go over the o.d. on the breech end of the barrel.

Interesting!

Later, Frank
Bartlein Barrels
 
#31
Re: Flute my new Bartlein or not?

Frank im looking to buy a 30 caliber barrel for a 300 win mag to replace a factory PSS rem 700 that is shot out, looking at a 29 inch finished barrel no fluting (to old to haul it around)1.25 at chamber end to 1 inch at business end, chrome monly to parkerize or coating of some sort, standard 300 win mag twist of factory barrel it shot very well. 168 grainers, 180, 190 i dont normally shoot anything heaveier tahn 190. threaded for can with cover would be nice, rifling open to suggestions 3 groove right hand?? i have 3 other barrels 3grove seem easier to clean? but tac drving accuracy is what im looking for as most people, Gary
 
#32
Re: Flute my new Bartlein or not?

An unfluted bar that has a diameter of 1.250" will weigh the same as a bar that has a diameter of 1.490" with 8 flutes 1/4" wide and 1/4" deep.
 
#34
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: PGS</div><div class="ubbcode-body">It saves a little weight. That's about it IMO.

If it's not done right, it can cut the shit out of your hand..... </div></div>

That's why they make deburring tools.
 
#35
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Edds</div><div class="ubbcode-body">An unfluted bar that has a diameter of 1.250" will weigh the same as a bar that has a diameter of 1.490" with 8 flutes 1/4" wide and 1/4" deep. </div></div>
The question is, which has less sag due to gravity. I know it's the one with the greater area moment of inertia. I can't calculate that with paper and pencil.
 
#36
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrm850</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">
That FEA is wrong, somehow. It doesn't pass the sanity test.

The .28mm (.011") deflection of the unfluted barrel is reasonable, but the .014mm (.00055") deflection of the fluted barrel is not reasonable.

No way can you hang 5lb off a 28" long, 1.5" diameter cantilevered beam (barrel) and deflect 1/2 a thousandth of an inch. No way. Something is messed up.

Not that it makes much difference, but is there a bore in your model? Diameter? How about rifling??? :) </div></div>

Whoops- You are all right. I'm not sure what parameter I had wrong but I re-ran the simulation and it came out much more like I thought it would.

The model was for comparative purposes so I just plugged 4340 in as a material because it was already entered into the database and I omitted the rifling. There is a .308" Bore however.

The unfluted barrel results were identical to the first test.
The Fluted barrel however was dramatically different. .32mm displacement.
Fluteddisplacement2_zpsb21f150d.jpg
</div></div>

Here's what I get, trying to replicate your setup:

barrel_zpsa0ff91f5.jpg


I get a max vertical displacement of 0.3390mm for the unfluted barrel, and 0.3748mm for the fluted barrel, for a 5 pound end load. That's about 10% more displacement for the fluted barrel, for the same load.

More interesting might be the natural frequencies for each - i'll run that later.
 
#37
Re: Flute my new Bartlein or not?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: waste_knot</div><div class="ubbcode-body">The question is, which has less sag due to gravity.</div></div>
The answer is,the fluted one with the larger diameter.
 
#39
Re: Flute my new Bartlein or not?

So, What I have now (barrel) is the stiffest.
1. If I flute it, it will be lighter but less stiff but it will be stiffer than a smaller dia. barrel of equal weight.

2. It should sag less and therefore vibrate at a higher freq. and lower amplitude compared to the non fluted of equal weight.

3. Chicks will dig me more with a flutted barrel.

Anything not true here?
 
#40
Re: Flute my new Bartlein or not?

In those pictures the fluted barrel will be heavier than the round one. For the weight to be equal the flutes need to be square. It won't change anything except the amount of difference.
 
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