I really hate to admit this but I need an assistant to load rifle magazines. I am using a 527 CZ 7.62 x 39 5 round mag in one of my conversions, I can get three rounds ok but the last two are a struggle. Case of old weak thumbs. What is out there in the way of loaders.

Your spring is too strong. No need for a mag spring to be that stiff for 4 rounds. I'm sure your fingers are fine.