384 on a .32 is fine, 2.19J. What you need is this (shameless self plug) https://angrybull.co.uk/tools/fps-converter/
Or....
I like this one better, you're sniping so stick in the sniper J limit (2.32 at most) and tell it what ammo you're using (0.32) and it gives an FPS you can't go above when...