I use a similar crimp technique for .45 and 9mm, with my Lee carbide dies, I set the crimp so that the case will easily slide into my Midway cartridge gauge (min), and also so that the outter edge of the case mouth is ever-so-slightly shiny from being turned in by the die. This produces a firm crimp that prevents bullet set-back (important for your .40's) and also ensures reliable feeding across the feed ramp for my Glock 19's and USP45.
This method was reached after doing excessive crimp and then not-enough crimp during the course of working up loads. Take your time and try several to see what works best. IME, too much is better than not-enough (within reason), but getting it perfect should be your goal. Best wishes,