I would stay away from the NC Star as I have gotten a couple used ones with guns, and they were both falling apart. That said, I have to ask a question when you say pneumatic airgun do you mean co2 or pre-charged airgun? Cause if you are talking about a spring piston gun they are very hard on scopes, and most will shift zero or just fall apart with most scopes. There is a airgun rated scope list on the web, can't remember the ULR, but it is there, however if you are talking about the pre-charged, or co2 most any close focusing scope will do.
I like Burris, and Bushnell, I also have an 8 to 32 X 50 Swift that is real nice, however some are like looking through a coke bottle, I had one like that, and another that's optics were just Ok. but the leapers and few other are good to. Most of the lower powered scope are very usuable, but when you get above 15 power that is the test of optical quality.
Again springers need really, really good scopes