bradh has is correct. When the 50 are charged and in the block, I tap the cases and the LOOK. If you are using the indexing type of press, after the powder is dropped, and prior to placing the bullet, have your loading light set so as to be able to see into the case...you should be able to rapidly develop the ability to see if there is a powder discrepancy. Has worked for over 70 years for me, and I am currently using the indexing for handgun, and remove the indexing rod for long-gun loading..
Best of Luck