Spiral fluting a ready made barrel!

[NORZ]

I just got a new .308win barrel for my Sauer STR. Its perfectly fine and shows awsome accuracy potentials. But. It is almost a bull contour, not a full-bull-contour but very close and really, really heavy. I want to cut flutes in it to lighten it a bit, my calculations show that fairly deep straight flutes will not cut the weight down sufficiently for my likings, but SolidWorks and its CAM extension with spiral fluting cuts seems to get the weight down to what I would like it to be but retaining its stiffness.

To make a long story really short..... Can it be safely done?

 

[Greg110]

Just a question here please. Have you thought about how you are going to relieve the stress of machining? That may well be a fairly serious issue.

 

[Preacher]

If it's showing awesome accuracy I for one sure wouldnt be fluting it... other than that there is not a problem doing it, and then maybe a trip to a cryo treatment place to relieve any stress that may have happened.. and then hope it still shot as good..

 

[Erik Cortina]

Don't fix what ain't broke!

 

[NORZ]

I did think about how to stressrelieve the barrel after machining, but cryo was my only thought.

The barrel is really heavy, but on the other hand, it has serious accuracy potentials.

This gun is meant to be carried around on my back with biathlon sling.

Sorry guys. I guess I´m just crying/complaining about somthing that cant be solved.

I´m just gona pack more Ibuprofen then, for my back.

 

[RonAKA]

A few issues. First you will not retain the stiffness. Yes, if compared to another barrel that weighs the same, but without flutes and of course smaller in diameter, it will be stiffer than that barrel. But it will not be as stiff as the original fat barrel without flutes. The other issue is that the barrel will have stress in it before you start, and you will relieve some of that stress with the fluting. The inside diameter of the barrel will likely increase and may go out of round, and the whole barrel may bend or twist. The likelihood of that happening will depend on how the barrel was made. The worst barrel for residual stress is going to be a hammer forged -- especially cold hammer forged. Next is a button rifled barrel. Least likely to be affected is a cut rifled barrel.

So it all depends on your tolerance for risk, and what type of barrel you start with. Hart Barrels flute if requested but only before the barrel is finished. They leave the lapping to the last step so the bore can be lapped to a consistent diameter, by removing the effect fluting has on stress removal.

 

[HiredGun]

I'm thinking rather than cutting big groves in it that essentially turn the thing into a crude coil spring I would either straight flute it or have the profile cut down to fit your needs. Just a very little bit off the diameter will lighten it far more than any fluting job. My opinion is deep sprial flutes are bad news on a barrel.