For everyone suggesting weighing individual charges or using a flashlight over the loading tray to check the charges in quantity - the OP is using a Dillon 550. Those suggestions are fine when using a single stage press, but are contra-indicated when using a progressive.
Now, that said, I put a Hornady powder-cop die in the third position on my 550b, and moved the seating die to the 4th position. And set the seating die to just barely straighten the bell out. I then run every round back through the press with the crimp die only installed in a second diehead. Yes, it's a second run through the press, but after finding a squib load the hard way, even though I (thought I) was looking in every case after the powder drop, I'm willing to run the extra step. With the P-C die installed, the last batch I did was a bit over 200 .45ACP rounds in about an hour, so still much faster than using a single stage press.
I've only used the P-C die on the .45ACP rounds since I got it. Going forward, I won't load handgun ammo on the Dillon without it. Rifle ammo? I can use it or not. I probably won't, because I actually like the assurance of the following method.
Here's the process I used for semi-auto rifle rounds, like .223 blasting ammo without the P-C die. The powder charge in these rounds is sufficient to more than offset any variations in empty case weights. I add the grain weights of the shells, bullets and primers. For illustration purposes, lets say the components sans powder weigh 200 grains. Using 24 grains of powder per round means that if I set the beam scale to 435 grains, I can quickly put two finished rounds on the scale, and if together they weigh more than 435gr (sufficiently below the weight of two loaded, primed rounds to account for variations in individual shell weights), both shells have powder. If either or both were to be missing its powder, they wouldn't tip the scale. This doesn't prove that they both have a perfect powder charge. If I'm keeping the powder hopper full then I'm assuming the 550b is dropping the proper charge each time I pull the handle. If I want "perfect" charges, I'll go back to weighing individual charges and using the single stage press. But for blasting ammo, this works for me.