What is the lightest possible barrel that can fire a 6.5 creedmoor? I've got a 20 inch barrel in mind. I've seen featherweight contour barrels at 2 lbs for 23 inches, so a touch under 2 lbs at 20 inches. Can a featherweight contour barrel be fluted? Is there a barrel lighter than featherweight contour? I just want to know if it's possible to do safely--not if it's a good idea.

You should keep the barrel thickness to .150" wall at the muzzle. If there is enough meat in the barrel to flute it, then the barrel isn't at it's lightest contour.

You must shoot off the bench only.

Charley Robertson at Score High Gunsmithing makes a "lightweight packer". I have one in 6.5 Creedmoor.

It has a custom contoured, 3 step tapered featherweight barrel that is the thinnest and lightest I've seen. Started life as a Bartlein 2B

You can get a Douglas #1 contour in stainless. That barrel is the basis for most short action NULA rifles. I have one chambered for a 260.

Titanium.

Some barrel makers refuse to make their thinnest contours in SS. Riley's 25-06 has a SS Pac-Nor Hunter weight barrel, their lightest, and it seems mighty whippy...

I'd be asking this question to a couple different barrel makers. Pacnor Lilja and Hart would be a good place to start.

You can have a good smith turn a tube to a lighter contour that FW,
my custom .270win was a Shilen moly tube .510" @ muzzle(24") and it gave 3/4" groups...
so with .264 cal you can go even smaller dia. if you so wish.

Factory pre64 FW contour rifles(.565" muzzle?) were chambered in .358win , so doing the math one can see
they also had very thin muzzle wall thickness.

I just stopped at my local smith today. He had a deep fluted (6 flutes) Schneider #2 on a Rem Model 7 that I was eyeballing. Not sure how much sidewall it had, but I would certainly trust him.

I think it was a 7mm.

My 9.3x62 is .590 at the muzzle. Shooting a bunch of rounds in quick succession heats the barrel up quite fast, but for hunting purposes, it's quite nice to carry.

Fluting does not make sense to me in an ultralight barrel. Do people think that it allows the best stiffness to weight ratio? I have heard many smiths state that fluting introduces stress to barrels.

I think that the Remington mountain contour is lighter than a FW and I know from experience that it can shoot quite well in 260, so a 6.5 creed would be no problem.

A bunch of the barrel companies will set you up with a mountain contour. at 20" it would be darn light.

A true Win FWT contour is the best for balance on a light rifle.