What is the heaviest bullet that will remain stabilize at 1150 fps in a FA 454?

I have a 380gr mould that was made for a longer cylinder 5-shot Ruger. Using shortened brass to allow the crimp groove to work with the shorter FA cylinder, it stabilizes at 1400fps but I have not driven it slower.

Long while back I tried some 400 gr. that seemed to be ok at 100 yds., but like you was pushing them at 1440 fps. I guess I will load up a few to see for myself.