Barrel fluting

[mike_l]

thinking of fluting my newly built .300 ultra mag but got scared off by the barrel maker who said i will ruin the barrel if i do this. he said that the only way to properly flute a barrel is to flute it before it goes out for lapping. is this true? any help would be appreciated.


mike

 

[winmagman]

Mike
I spent some time in Mike Rock's shop (Rock Creek Barrels) and he fluted his before they were rifled. If I remember right it has something to do with fluting process changing the bore diameter slightly, I think.

 

[mike_l]

thats what i was told but have herd several people speak of barrels that they fluted after every thing, chamber, threads, ect. and clam to shoot very well. that is why i am asking.

 

[winmagman]

I've heard/read of folks that have done it as well and as a very general rule the heavier contours seem to be less affected by the process than the thin sporter contours.

I've got no scientific evidence, just rumor/hearsay/opinion, so take it for what its worth.

 

[Agunner012]

Don't do it! Wait till you shoot out the barrel and are ready for a new barrel. Then order a barrel fluted from one of the top barrel makers. You run the risk of ruining a good shooting barrel if you flute it now!

 

[Waffen]

Wouldn't you want to flute the barrel only BEFORE the last stress releaving cycle you put the barrel through?

 

[Black Diamond 408]

I have fluted bbls after i recieved them, they all shot very well. I didn't really know that the bore dia could change due to stresses the tooling imparts on the steel. I called several bbl makers and asked them what should i do, i got conflicting reports, one said the bbl is ruined, others said you may need to stress relive it agian and re-lap, and another said just shoot it. The big trick is dont remove much metal on each pass, take your time, this way your not building up massive amounts of stress.

I dont flute bbls anymore, unless its a test gun for my personal use.
My 338 snipe-tac, (personal gun) was used for a test rifle.
I wanted to see just how much weight i could get off the bbl by using very large flutes. I used a 31/64th end mill, they are deep! Before fluting the gun would shoot .5moa... after fluting the gun shot 1moa, i felt sick...did i ruin the bbl? I totally cleaned the bore and used moly powder to burnish the bore, re-broke in the bbl. After 20 shots the fouling was gone and groups were back and even better, .2moa was this just a fluke? Probally

In my opinon, have the bbl fluted when you order it. This will be the best option. If any thing it will give you peace of mind.

 

[Bart B]

Winmagman's right. Fluting a finished barrel will change its internal dimensions. Here's what happens.

Button rifled barrels will have a tight spot at the ends of the flutes and be a bit larger under the flutes.

Hammer forged barrels are the opposite of button rifled ones; larger diameters at the ends of the flutes and tighter under the fluted parts.

Cut rifled (single point or broached) barrels will change a tiny bit but not nearly as much as button or cut rifled barrels.

Having watched some fluted finished barrels air gaged with that great Sheffield device, the ball in the gage tube jumps as the gaging head goes past the ends of the flutes and lets more or less air get by it. Under the flutes, the ball stays pretty stable but at a different place than in the non-fluted part of the barrel.

And fluting a barrel removes steel that helps make it rigid. Fluting a barrel makes it less rigid/stiff than before. But a fluted barrel will be a very small amount stiffer than a solid barrel with the same weight per inch. Fluting adds a small amount of surface area that lets the barrel cool a bit faster; typically less than seven percent faster. A coarse sand blasted barrel will cool faster than a fluted one. If the barrel's properly stress relieved after rifling, it won't shift point of impact as it heats up; something fluting will not fix.

If you must have a fluted barrel, ensure its maker flutes the drilled blank before he reams it to bore diameter and puts the rifling it. Make sure its maker then laps the rifled bore and gages it for uniform dimensions before you get it.

 

[mike_l]

thanks for the help. guess i will leave it alone and deal with the little extra weight and looke of a non fluted barrel. don't want to risk loosing accuracy for saving weight.

 

[EddieHarren]

I have had many barrels fluted for customers. None of these barrels were fluted before drilling, reaming and chambering.
Most of these barrels were LV,HV, or Hunter taper. I cannot recall any adverse effect on accuracy in any of these barrels. In fact one of the barrel makers that I buy the barrels from does the fluting. I will add that when he flutes a barrel, he takes light cuts on a fully supported barrel and lots of coolant.

 

[Boss Hoss]

If it is done right it will not be an issue. Speedy Gonzales flutes all of his barrels and has set world reacords with them and has fluted over 10 for me and never an issue. Don't believe everything you read on internet forums. Everyone told me the same thing including the barrel makers but it has to be done correctly!!

 

[Wild_Bill]

Hi with diferent barerels the fluting is done at diferent times usualy with a cut barrel it is profiled and fluted before the rifling is cut but with button and hammer forged barrels the fluting is cut after the rifling is cut. I have lapped all three barrels and if the fluting is cut to deep and with to heavy a cut the barrels will have tight and loose spots at the end and start of the flutes. Sometimes it can be lapped but other times it cant recently we had a barrel that was realy tight at the end of the flutes so we cut ti back from 30" to 28" and deep hole crowned the barrel back into the flutes and the tight spot was removed it is a very accurate rifle and the new owner loves it we did not pay the manufacturer for the fluting as we stated that if we had to we were sending it back as we could not sell it for the extra price. All barrels that have been fluted MUST be re stressed relieved after fluting this will make sure they are ok and stabalise. If you want it fluted go for it but send it to some one that will do it correctly and they have the equiptment to Chro it or stress relieve it after fluting and you will be good to go. Now one thing to make sure of is that the money you sink into this barrel is worth it if the barrel is not going to last much longer just shoot it out and then rebarrel with what you want. Also if it only shoots OK not great it will nto likely shoot any better after fluting. As stated above a fluted barrel of the same length and weight will be stiffer but 2 identical barrels one fluted and the other not the non fluted barrel will be stiffer only you can make the choice.

Cheers Bill
Australia