Centaur 1

I'm probably wrong but I'm under the impression that heavier than lead shot may damage a choke tube which isn't designed for them. This is because a shotgun barrel is thin to begin with and then they bore out the muzzle and cut threads which makes the barrel REALLY THIN. If you don't install a choke that is rated for tungsten shot then the choke could start to bulge which would ruin the barrel. As far as a fixed choke barrel goes, I was under the impression that you could use any load.