By shaking them I know there is at least some powder in them, and the likelihood of the powder measure dispensing a wrong dose of powder is very low.

By weighing all of the cartridges I know there is a high probability there is no double charge of powder. The weighing exposed the two duds, one with the 22 LR case inside of it, the other one with no powder.

I have a strict process on the progressive press of looking inside a charged case every time before inserting a bullet - still I managed to produce one cartridge without powder and another without even a bullet!

Yesterday's loads were a bit challenging to check the powder level visually as the amount of powder was very small compared to the case capacity. I was making silly low power loads mandated by Cowboy Action Shooting safety rules. I have two lamps specially directed into the press to highlight powder level and I also removed a charged case a few times when I could not see well, and still a break in concentration resulted in the above mentioned incidents.

This was a lesson that reminds to give the reloading process your whole attention or not doing it at all.