I haven't used Cabot (Haynes?) 214 but Inconel 718 was my go to material for lots of structural applications in my gas turbine (jet) engines. Even Claypipe would like it! It's 184,000 ultimate tensile, 148,000 ultimate yield and 19.9% elongation aught to make one hell of a cannon barrel. Even at 1200*F it still has over 140 KSI tensile, 120 KSI yield and 18% elongation so shooting it in Phoenix, Arizona would be quite doable. Of course, there's the little matter of machining it.