.380. At the time the smallest was a PPK/S. Too big, heavy, and bad trigger. Not all that accurate. 380 was expensive, and difficult to load.
9MM:
Same size bullet as .380, hard to seat with big fingers, not all that easy to get the guns to be accurate loading for them at that time.
.44 Special:
Not enough quality CCW guns around. Big case, great round if handloaded to potential, but no guns except .44 Magnums to shoot it out of at that level, and time. .44 Bulldog was it, and wasn't up to the task.
These were all a long time ago, so the reasons for most have changed.
I now carry a 9mm sometimes.