Ron,
Welcome to the forum. Please come back often.
I was also successful using Winchester USA ammo, the so-called Winchester White Box, which is commonly found at Walmart.
My policy was that the pistol must always, without any exception, fire the contents of two magazines without errors. That achievement should more than satisfy its use as an emergency pistol for up-close defensive use.
Kahr and Kimber pistols need a break-in period. However, the R9 should be ready to go out of the box.
I think that frequent cleaning will be necessary to ensure error-free operation.
The R9 is not a range gun, of course. The pain would be too great anyway.
I hope you enjoy your pistol, and the many fine people here on the board.
Bill