Did it not cock the hammer every time, or did it get worse about it as the day went on? If it was good to start with, but then started to not cock the hammer, that sounds good for the coating on the steel cases.
When I got my first 92FS, I was told that the pistol was made for 124 grains, and that would be the best to run in it. The guy told me that it may work with 115, but it could cause a problem. I have run 115 in my first 92FS (grabbed the wrong box and then tried it), and it worked fine, but I still try to only run 124.
Hope that helps, and hope you enjoy your new Beretta.