Re: TITANIUM barrels??
We make all sorts of wild stuff from Ti in the aerospace industry and the high-end motorsports industry. Hollow steel, polished ID drive-shafts that weight ~1lb and transmit hundreds of horsepower on endurance cars are NOT made from Ti. They're made from 300M almost exclusively. Ti doesn't have the fatigue properties that the Steel does.
Ti shines in AL replacement applications, especially at elevated temps (300F+ enviro) because of its critical temps and increased fatigue limit over AL.
Top level AL, like 7000 series has a reasonable fatigue limit around 7ksi. Yes, AL creeps and never has a true endurance limit but it's a safe bet that you can get 10^8 cycles from a <7ksi application in AL for a material density that's appx 0.11 lb/in^3
Most of the Ti we use in aerospace is alloyed, not pure Ti, and much of it is functionally an endurance limit of about 19-20ksi for a material density appx .16 lb/in^3
That is ~ 300% increase in fatigue limit for 160% increase in component weight, so you can make something that is FATIGUE CRITICAL lighter from certain Ti Alloys than you can from AL.
Not true with steel, but Steel is much more prone to oxidation and has it's own problems to work around.
Titanium is not the magic material that many people think it is, it's great in some applications and it absolutely stinks in others.
Take a Ti suppressor for example. If you can make it live in AL you get a HUGE improvement in the heat conductivity of the AL (almost 20x's, geometry and heat path dependent) than you do over Titanium. AL is soft and does not take abrasion and ablation well at all. AL makes great 22 suppressors but it's tough to make it live in a centerfire suppressor due to the reduced material properties at elevated temps, blast pressures, and the Mach 5 sandblaster effect that is the blast chamber.
My 22 suppressor is a monocore so I get excellent heat transfer along the baffle stack and the only reason that I used a piece of DOM Ti-6Al-4V Grade 5 for the envelope instead of a piece of AL is because I got a piece of from an airplane that I helped to build. It has a special meaning to me and it's a 22 suppressor, otherwise I would have made it from a piece of AL tubing and kept the weight and heat transfer benefit.
On the actual topic of Ti barrels: You COULD make one from it but the cost of the material alone is going to be around the same as a completely finished, installed, and ready to shoot SS416R barrel. Then you add all the special considerations for how it needs to be machined, the special cutting fluid, cutter geometry and composition, etc. and you're looking at something that is going to be WILDLY expensive only to have a sub-par performance.
You want to save weight on a barrel? Drop the contour substantially and run it that way. There's no need to run an MTU contour for <1/2MOA performance. I've seen it and owned rifles that perform to demonstrate contrary to that belief.