>>3171>main problem is that it doesn't do high temperaturesYeah. Could the interior be coated with a less heat sensitive material somehow? I guess in the end you would run into the same problems as with more traditional materials, with overheating of the barrel causing warp.
https://www.ar15.com/forums/ar-15/How_hotin_degrees_Fdoes_an_AR15_barrel_get____/118-160030/
Not sure what the most accessible material for a decent barrel would be. Perhaps casting or using electrolysis to rifle a suitable piece of steel?