If they were shot in a full auto this could be a problem , but my guess is lube the inside of the case neck make sure the shell holder and the die make firm contact each stroke, good luck
LISTEN TO THIS MAN
PLUS, YOUR GRAND WILL NOT CYCLE SO YOU HAVE A SINGLE SHOT
good chance you will screw up your grand.
at the slow of speed that big bullet will not stabilize or better yet will stick in the barrel just waiting for the next round