I thought all the 3XX Airlite series revolvers were scandium frames. They started out with the picture of the atom on the side and were a similar but different shade of light gray than the regular aluminum alloy frames for the 6XX Airweight frames. Personally I don’t see why you couldn’t put a titanium cylinder on a regular aluminum alloy frame. The new Airweights are all +P rated so the minor weight change in the cylinder shouldn’t do anything as long as you stick with .38’s. I would hesitate to run .38 +P through it only because that is getting to be a handful of recoil in a now even lighter gun. And I don’t think you are talking about running the volume of ammunition through it that it would take to start wearing it out. Lastly, I’m not sure you would really feel the minor weight difference as you carry it. I would try a lighter weight grip and or trying 110 grain ammo before going all mad scientist with a J.