These are my guesses, some of which have already been mentioned.
1. Browning P35 had the 9mm market covered for single action fans.
2. 9mm wasn’t nearly as popular then as now. It was viewed as watered-down euro-trash.
3. Why use a Luger when you can be Super?
4. Americans didn’t like metric cartridge designations (or Germans) nearly as much back then.
5. Why use someone else’s cartridge when you can use your own?
6. Why use a cartridge with a shorter OAL when a longer one fits in the mag? The longer one gives you better feeding and velocity.
