I have a couple NiB carriers but have not had any problems with either.
I would recommend educating yourself about NiB and how it works. NiB has a high number of microscopic high points. Because the high points make all the contact, there is less surface area for friction to occur. The problem with this is once the high points wear down the coefficient of friction increases due to more surface area being contacted. NiB is not self-lubricating like Teflon. If you see wear on the high points, NiB has lost its friction fighting capabilities. Additionally, these high points and their corresponding ridges tend to capture carbon fouling. A NiB carrier will require more cleaning than a NP3 carrier, for instance.
If you're building a gun with an eye toward a relatively high round count, I agree with Dan, the Melonite coating is probably the best on the market today. Melonite actually bonds with the steel on a molecular level.
