Model 100's coming from the factory flatten out as there is nothing to keep them shaped. Normally, holding the new holster in your hand with the seamed edges between your thumb and the opposing fingers and squeezing will open the holster wide enough to fully seat the gun. Leave the gun in the holster overnight and you won't have any problems.You were right, I did not like the fit of the #9. The trigger guard interferes with the holster preventing the gun from going all the way in.
At what position do you find the most comfortable to carry?
Please don't shop Bianchi holsters by "sizes" because those references are really "families" and don't directly refer to size. Code 1 fits J-Frames (small), 4 fits medium/large Taurus revolvers (not small) and up the list at 7 you're back down to Beretta 3032 (pretty small).
19226/19227 (09) are the listed fit for Bersa Thunder .380, Walther PPK and SIG P230/232 and I know from my own experience that they do fit and they fit well.
19230/19231 (10) are the recommended holsters for Colt Officers and CZ 75 Compact. I just don't see how that can be a decent fit for a Bersa.