Do you have Leading in your bore?
If your bullets are too small, they may keyhole. If your bullets are too small, you will probably have significant Leading in your bore, with the gases blowing by the bullet stripping Lead off the bullet, and depositing it in the bore. A non-jacketed bullet can be too small before it is loaded, or be sized to too small during loading. If my understanding is correct, your bullets are cast, and then coated.
I like Beretta and Walther 9mm pistols. My measurements are that their barrel groove diameters are about .3575". You need a micrometer to measure, not a caliper. One of the ways to prevent bullet set-back on feeding is to have lots of neck tension holding the bullet in place. Lee even makes a "U Die", which leaves both the ID and OD of the case smaller. If your bullet is soft, it probably will be swaged down some. The bullets I cast, I cast big and really hard, to prevent this.
One can set up a die system of sizer & expander, which leaves the case ID about the diameter of the bullet, down to where the base of the bullet rests, then is smaller below that. I am experimenting with such a system, using it for hollow based swaged wadcutters in .32 S&W Long. These bulets are as soft as can be. Results so far have been excellent. No Leading.