Fluting a bull barrell ........good idea?

[Truegent2004]

I'm thinking of getting a DPMS Panther Bull Twenty (20 inch stainless steel bull barrel). I'm not that crazy about the guns weight, 9.5 pounds w/o scope and mount. I've read several articles arguing for and against barrell fluting.

I know it increases barrell surface area for faster cooling and makes the barrell lighter. Nobody seems to argue a change in accuracy.

Whether or not it makes the barrell weaker is the hot debate.

For $65, DPMS will give my barrell full flutes. Ok.........bring on the advice........

[zhunter]

I will not affect accuracy, MANY sniper rifles are fluted to cool faster and to be lighter to "HUMP"!!!

[sfinney]

I read somewhere that fluting actually increases barrel strength and rigidity, less barrel whip etc.... in addition to the cooling properties, and lower weight. Something to do with all the extra angles cut in the barrel adds stength? Is that true, or BS?

[TwoShot]

Given two barrels of equal length, diameter and caliber, the non fluted will be stiffer. You cannot remove material from a barrel and make it stiffer. However 2 barrels of the same weight, one fluted and one not, the fluted barrel will be stiffer.

[Huck]

Flutes are awesome if they are done perfectly, they suck if they aren't. If they are not evenly spaced and the same length your POI will shift as the barrel heats up. I have a heavy barrel and I am probably going to either shoot it as is or turn it down on the lathe, I'm kinda of skiddish of the whole fluting thing. The snipers and target shooters that are using fluted barrels don't shoot 30 + round strings like we do.

[warpspeed]

Truegent2004,

Have you read this thread ?

I think that a standard profile barrel will be the weight you are looking for,

[smokshwn]

There seems to be a lot of either bad info or maybe misunderstood info out there about fluting (I was ignorant myself). I just got through getting a thourough education from a friend of mine who has been building rifles for the last 30 years. I will try to condense what he has been teaching me.

1) Fluting does not stiffen a barrel. Stiffness comes from the relationship of the diameter and length. Shorter = stiffer. Larger diameter = stiffer. Now the application of this info. given barrels of the same length, a bull barrel with no flutes will be stiffest, the same barrel with fluting will be lighter and less stiff, and the same barrel turned down (decreased diameter) to the weight of the fluted barrel will be the least stiff.

2) Fluting/cooling. Yes fluting can possibly increase cooling by reducing mass and increasing surface area, however it is difficult at best to determine how much this affects POI compared to the original diameter barrel which with more mass can take more heat before a POI shift.

3) Fluting/accuracy. As has been previously stated the fluting must be exact or else inconsistent expansion will cause POI shifts. As well as it is best to have the fluting performed prior to heat treat. As I understand it, fluting post heat treat/tempering will possibly cause POI shift.

4) Damn they look cool.

5) Improperly cut fluting or damage to the barrel from the fluting process can make for incredibly beautiful metal sculpture. The following Kaboom was thought to be from caused by poor quality control in the barrels supplied to AI.Fluted Kaboom

Take care, Craig

[EricW]

Sorry to be the wet blanket, but fluting will do exactly diddly squat to make a barrel cool faster - unless it's bolted to an airplane or helo. It's really, really old engineering non-news. Thompson fluted their sub gun barrels back in the 20's and subsequently quit when it was realized that all it did was make the gun cost more. Air has to move across the fins at a fairly good clip for them to remove a meaningful amount of heat.

(And yes, I realize a lawnmower engine has cooling-fins. It also has a fan that blows air across the fins.)

I do think fluting has a lot of merit - especially on MOR's with 26"(and +?) barrels. Shoot an unfluted bull barrel offhand for any length of time, and you will see the virtue in fluting.

[Philip Dedmon]

I have a 16" DPMS Bull Barrel that Tommy fluted for me. He cut 6 flutes under the hand guard and 6 flutes out pass the the gas block. All flutes are 5" long & .125 deep. So far I have not see any change in accuracy. I am very pleased with how the rifle points & swings now. Best I can remember this got about 5 ozs. off the rifle. I am thinking of taking a 20" bull and cutting it to 18" for another rifle I am working on and when I do I am going to have him flute it the same way.

[tightloop]

Very cool looking....

[kellyn]

Fluting's only function on a race gun is to look cool.

I have three fluted barrels and they all shoot just fine. Derrick Martin did the fluting and he knows what he is doing. But if you want a lighter barrel, turn it down.

EricW is right on about the cooling effects of fluting on a normal AR style rifle. If you want cooling, make a water cooled gun (that would be cool) or the JP heat sink.

[Loves2Shoot]

You mean my new wiz bang AR that is fluted isn't better than my mil spec barrel? Dang!!! It sure does look cool though

[Wap wap]

Take a look at the Remington Stainless steel fluted barrels on their varmiters and also Kimbers, Both guns (have one of each) shoot just as tight as groups as the full contours (have those also). Do I feel the cost is worth it? In this case yes because the fluted barrels are walking varmiters and carry better. Most AR with heavy barrels, are to front end heavy anyway. I do it to restore the balance of the gun.

[Truegent2004]

Thanks for all the great input guys!! Today I ordered an Artic Panther(minus the white finish on the receivers and teflon treatment on the barrell; saved $100) with ambi-safety. I will probably put an Armalite one piece mount and Weaver scope(2 x 10 x38mm) on the top.

Sad to hear the DPMS back log has gone from 2 months to 3. Oh well, should still be here for summer.

[Gun Geek]

Just got the new Burkett video.

Matt and JP talk about fluting. FWIW they are against it:

-Doesn't help cooling

-Can cause POI shifts as barrel heats

-Better results achieved with re-profiling

-JP sells aluminium fins that they claim cool much better than flutes (more $$)

Net is no positive that can't be had another way+potential negatives => don't do it.

Their discussion is in the context of ARs and 3-gun. But I think Matt makes a comment that he thinks that it applies to MORs as well.

In a hunting gun, where the cold shot might be the only one you get, after lugging the thing up and down the mountians for 3 days, flutes might make sense to reduce weight.

[Mickster]

I am thinking of taking a 20" bull and cutting it to 18" for another rifle I am working on and when I do I am going to have him flute it the same way.

Philip, how did this project turn out?

I have a 20" bull that I'm thinking about cutting back to 16" just to have the short barrel with long gas system. Will I have to change the size of the gas port? If so, to what size?

Since I got the upper off a prize table and a friend has a mill and lathe, my entire investment would be $28 for the 1/2x28 thread die and that's it which is very good.

Anyone have any comments on this modification?

[Mickster]

Anyone at all? Please chime in.

I also want to cut down the o.d. of the barrel from the gas block forward after cutting and threading it to 16".

Am I about to wreck a perfectly good barrel or will this mod actually make for a pretty decent little rifle for 3-gun?

There's a lot of you guys that know much more than I do about this sort of thing. What's your take on it?

[chp5]

Anyone at all? Please chime in.

I also want to cut down the o.d. of the barrel from the gas block forward after cutting and threading it to 16".

Am I about to wreck a perfectly good barrel or will this mod actually make for a pretty decent little rifle for 3-gun?

There's a lot of you guys that know much more than I do about this sort of thing. What's your take on it?

Mickster - I don't think you can cut a 20" down to a 16". I've had a 20" cut to 17", but not 16". 18" is the most common length.

My 17" will cycle any good, powerfull .223 with 100% reliability, but the underpowered Wolf stuff will sometimes short stroke. There's a thread on this topic somewhere here.

[Mickster]

I've been doing some internet research on this little project. I'm no gunsmith but here's what I plan to do.

I'm going to cut the 20" DPMS bull barrel down to 16". Turn it down from the gas block to the end to .750. Turn down the last 5/8" to .498 and thread it. Then turn down the under the handguard area to .850. Finally I'll open up the gas port from .625 to .700 (18mm).

I'm doing this mod first thing tomorrow morning so if it sounds like a disaster waiting to happen, somebody please stop me.

If it sounds pretty good but needs some changes, please inform me.

Would 17" or 18" be better? What problems will I run into.

Any advice will be appreciated.

[rpmwfo]

I've been doing some internet research on this little project. I'm no gunsmith but here's what I plan to do.

I'm going to cut the 20" DPMS bull barrel down to 16". Turn it down from the gas block to the end to .750. Turn down the last 5/8" to .498 and thread it. Then turn down the under the handguard area to .850. Finally I'll open up the gas port from .625 to .700 (18mm).

I'm doing this mod first thing tomorrow morning so if it sounds like a disaster waiting to happen, somebody please stop me.

If it sounds pretty good but needs some changes, please inform me.

Would 17" or 18" be better? What problems will I run into.

Any advice will be appreciated.

I just had Wakal (Dreadnaught Industries)cut down a CMT 20" barrel to 17" before the holidays. Did a real nice job with outrageously fast turnaround. I built it up into an upper and took it out for testing. With Q3131A Nato stuff, it would lock the bolt back, but with standard pressure stuff it wouldn't. I pulled the front sight and opened the port to 0.106". Works like a charm no with anything I feed it. I thought about 16" but decided I wanted something a little longer for insurance on functioning with the rifle length gas system.

[Mickster]

Thanks rpmwfo,

I'm on my way to the machine shop in an hour. I'm taking your advice and going with 17" and opening the port to around .104 using a number 37 drill. That should work OK.