New CALIFORNIA P380 owner- FTF issues-Magazine problem?

**2 days of cycling the slide approx. 150 x in total. 2 nights of leaving the slide locked back

-First 150 rounds of (Blazer 95 grain FMJ) with gun out of the box after internal inspection.
-Found no Lube though surfaces felt oiled
-Found gunpower residue as I guess during factory test fire



-Range: I had three mags (two-6 round and one 7 round)
Loaded all three and repeated until 150 rounds fired.

*multiple FTF issues with each mag which did not improve over the 150 rounds
*Able to clear each FTF by pulling the slide all the way back and releasing it. The bullet then entered each time.
*One of the 6 round mags worked the best with multiple NO FTF issues. I marked that mag for later ID
*Returned home and cleaned internals and oiled per manual with light gun oil
*Used Flitz polishing lightly on feed ramp and throat with a dremel tool.

Questions: Why is one mag better than the other two?
Is there a problem with the other mags?
What should I do next besides, of course, go back to the range for another 100 rounds?

...and yes, I did pay attention to a straight wrist and solid grip

Thank you for your responses,
Bill