I know what there web site say's and I read Frank's post on this thread.So read my post correctly.I said quote [If It Is Done Correctly] meaning all aspect's of the fluting process.[Depth.Stress Relief after fluting,lapping after fluting]and anything else I am missing.
To clarify a few things for everyone......
Again I would never flute a button barrel because of the stress induced from button rifling and no way of measuring it/check for stress......if you hit any residual stress points the secondary machining operations like fluting, contouring the barrel or even cutting and crowning it....if you hit any stress point the machining operation will relieve the stress and the bore will open up on you. How much does it open up? This will vary with the contour, type of machining etc....the last place you want it to open up is right at the crown though. I won't say which semi custom factory rifle we had in the shop a couple of years ago. It was a button rifled barrel in .22-250 and it was factory fluted. The guy could never get the gun to shoot under 1" groups. Sent it back to the factory and they told him it was fine and sent it back to him. He brought the gun here and the first thing we did was measure the bore. As you pushed the bore gauges down the barrel you would see the bore literally move a full .001" up and down on the gauge as you pushed it down the bore. We replaced the barrel with the same contour, fluted it etc...and the gun shot like a million bucks.
Most of the time we flute the barrels after they've been rifled and finish lapped. Yes we've fluted before rifling but with not inducing any stress into the blank during rifling we haven't experienced the bores going sour etc....
To give you all an idea on the depth of flutes vs. contour etc....
Barrels up to a .750" muzzle diameter we will only go approx. .050" deep.
Barrels from .775"-.875" muzzle diameter we go approx. .075" deep.
Barrels with muzzles around .900" and larger we go .100" deep.
A couple of months ago we got a barrel back from a customer to have a look at it. Believe it was in .260 if memory serves me correctly. The barrel had been chambered and installed and shot just fine. It was a straight taper barrel like a MTU or a M40 type. After it had been shot some it was decided to flute it (we didn't flute it) and the flutes were approx. .175" deep. The customer always had unexplained flyers and it was no longer consistent. I'll guarantee it was from the depth of the flutes.
Will every barrel be effected? I will say no. The depth of the flutes, contour and the caliber (bore size/wall thickness) all plays a part.
I use to run fluted barrels on some of my comp. guns because I was trying to take weight out of the gun, help with cooling and I thought it looked cool! But I don't run fluted barrels anymore personally, not that I have anything really against them but if I want to save weight as my primary reason I'll drop the contour size.
Any questions give me a shout! Happy to talk to anyone about the subject or help in anyway we can.
Later, Frank
Bartlein Barrels