Jbar4Ranch did you have the problem I had using 451 with the belling die making the case to large below the bell. I ended up using a very firm crimp to hold the ball in place.
Didn’t think about the grease but it was so slow I didn’t get much leading. Might be different with your 850 fps.
Did you use any filler?
Thanks for the input.
"The difference between stupidity and genius is that genius has its limits" Albert Einstine