I actually use strictly Winchester ammo for plinking, range and defense.
The SXZ is the Winchester USA ammunition with the addition of there Lubalox coating. I have ran it in my SR9, G21C and PX4 40 S&W with not one issue after more than 5,000 rounds. And The only gun I could say any appeared to be dirty in was my 21C thanks to the compensator.
I use the USA or SZX for plinking and the range and BlackTalons for home defense.
Also I have done comparissons between all of the Winchester stuff and have pictures of each type of bullet before and after each test.