I would wonder if a tuner has less/no effect on stiffer shorter barrels?
FYI I tried one on my 600 mm barrel and didn't gain anything.
I also have a carbon fiber sleeve on it. So I guess it is pretty stiff. I took it off but haven’t tried it yet. If the stiffness creates a short barrel vibe I’m thinking just adjusting fps will get it tuning in the right direction!