Robert,
My .02.
First, a good point wasa made above about switching to a 9mm. I would take it one step farther. Start with a heavy .38/.357 revolver with target loads, then work up to full loads. Convert to 9mm, then the .40. Stay with each level until you have resolved the flinch.
A second trick is to start with magazines loaded with dummy rounds. Have a partner load a mag with one live round and the rest dummies. Slowly work you way up from 1 round to a full mag. All the time working on controlled firing. A sidebar, this is great practice for learning to quickly clear malfunctions.